Joomla's dev environment + NPM prep (ryersondmp#30)

Semi-major release!
- **Refactoring:** Refactored Sa11y's code to incorporate the Joomla team's development environment, tools, and language structure. (Source: [joomla-a11y-checker](https://github.com/joomla-projects/joomla-a11y-checker)
- **Accessibility fix:** Scrollable areas within the main pain are now keyboard accessible.

.editorconfig

@@ -0,0 +1,11 @@
+# EditorConfig is awesome: http://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+# Unix-style newlines with a newline ending every file
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+indent_style = tab

.eslintignore

@@ -0,0 +1,2 @@
+/bookmarklet/**
+/docs/**

.eslintrc.json

@@ -0,0 +1,18 @@
+{
+	"extends": "airbnb-base",
+	"env": {
+	  "browser": true
+	},
+	"rules": {
+		"max-len": "off",
+	  "class-methods-use-this": "off",
+	  "import/prefer-default-export": "off",
+	  "import/extensions": "off",
+	  "no-plusplus": [
+		"error",
+		{
+		  "allowForLoopAfterthoughts": true
+		}
+	  ]
+	}
+  }

.github/workflows/publish.yml

@@ -0,0 +1,22 @@
+name: "Deploy to NPM"
+
+on:
+  release:
+    types: [created]
+
+jobs:
+    release:
+        name: release
+        runs-on: ubuntu-latest
+        steps:
+            - name: Checkout
+              uses: actions/checkout@v3
+            - name: Setup node
+              uses: actions/setup-node@v3
+              with:
+                  node-version: 17.x
+                  registry-url: https://registry.npmjs.org
+            - name: Publish to NPM 📦
+              run: npm publish --access public
+              env:
+                  NODE_AUTH_TOKEN: ${{secrets.NPM_AUTH_TOKEN}}

.gitignore

@@ -1,6 +1,21 @@
+# IDE & System Related Files
+.buildpath
+.project
+.settings
+.DS_Store
+.idea
+.vscode
+node_modules/
 
+# OSX
+._*
+.Spotlight-V100
+.Trashes
 .DS_Store
-docs/examples/.DS_Store
 **/.DS_Store
 **/**/.DS_Store
-node_modules
+**/**/**/.DS_Store
+
+# Windows
+Thumbs.db
+Desktop.ini

.stylelintrc.json

@@ -0,0 +1,248 @@
+{
+	"plugins": [
+	  "stylelint-scss",
+	  "stylelint-order"
+	],
+	"rules": {
+	  "declaration-bang-space-before": "always",
+	  "declaration-bang-space-after": "never",
+	  "color-named": "never",
+	  "declaration-block-no-duplicate-properties": true,
+	  "block-no-empty": true,
+	  "no-missing-end-of-source-newline": true,
+	  "color-hex-length": "short",
+	  "color-hex-case": "lower",
+	  "color-no-invalid-hex": true,
+	  "indentation": 2,
+	  "number-leading-zero": "never",
+	  "max-nesting-depth": 4,
+	  "selector-max-compound-selectors": 5,
+	  "order/properties-order": [
+		"position",
+		"top",
+		"right",
+		"bottom",
+		"left",
+		"z-index",
+		"box-sizing",
+		"display",
+		"flex",
+		"flex-align",
+		"flex-basis",
+		"flex-direction",
+		"flex-wrap",
+		"flex-flow",
+		"flex-grow",
+		"flex-order",
+		"flex-pack",
+		"align-items",
+		"align-self",
+		"justify-content",
+		"float",
+		"width",
+		"min-width",
+		"max-width",
+		"height",
+		"min-height",
+		"max-height",
+		"padding",
+		"padding-top",
+		"padding-right",
+		"padding-bottom",
+		"padding-left",
+		"margin",
+		"margin-top",
+		"margin-right",
+		"margin-bottom",
+		"margin-left",
+		"overflow",
+		"overflow-x",
+		"overflow-y",
+		"-webkit-overflow-scrolling",
+		"-ms-overflow-style",
+		"clip",
+		"clear",
+		"font",
+		"font-family",
+		"font-size",
+		"font-style",
+		"font-weight",
+		"font-variant",
+		"font-size-adjust",
+		"font-stretch",
+		"font-effect",
+		"font-emphasize",
+		"font-emphasize-position",
+		"font-emphasize-style",
+		"font-smooth",
+		"hyphens",
+		"line-height",
+		"color",
+		"text-align",
+		"text-align-last",
+		"text-emphasis",
+		"text-emphasis-color",
+		"text-emphasis-style",
+		"text-emphasis-position",
+		"text-decoration",
+		"text-indent",
+		"text-justify",
+		"text-outline",
+		"text-overflow",
+		"text-overflow-ellipsis",
+		"text-overflow-mode",
+		"text-shadow",
+		"text-transform",
+		"text-wrap",
+		"-webkit-text-size-adjust",
+		"-ms-text-size-adjust",
+		"letter-spacing",
+		"word-break",
+		"word-spacing",
+		"word-wrap",
+		"overflow-wrap",
+		"tab-size",
+		"white-space",
+		"vertical-align",
+		"list-style",
+		"list-style-position",
+		"list-style-type",
+		"list-style-image",
+		"pointer-events",
+		"touch-action",
+		"cursor",
+		"visibility",
+		"zoom",
+		"table-layout",
+		"empty-cells",
+		"caption-side",
+		"border-spacing",
+		"border-collapse",
+		"content",
+		"quotes",
+		"counter-reset",
+		"counter-increment",
+		"resize",
+		"user-select",
+		"nav-index",
+		"nav-up",
+		"nav-right",
+		"nav-down",
+		"nav-left",
+		"background",
+		"background-color",
+		"background-image",
+		"filter",
+		"background-repeat",
+		"background-attachment",
+		"background-position",
+		"background-position-x",
+		"background-position-y",
+		"background-clip",
+		"background-origin",
+		"background-size",
+		"border",
+		"border-color",
+		"border-style",
+		"border-width",
+		"border-top",
+		"border-top-color",
+		"border-top-style",
+		"border-top-width",
+		"border-right",
+		"border-right-color",
+		"border-right-style",
+		"border-right-width",
+		"border-bottom",
+		"border-bottom-color",
+		"border-bottom-style",
+		"border-bottom-width",
+		"border-left",
+		"border-left-color",
+		"border-left-style",
+		"border-left-width",
+		"border-radius",
+		"border-top-left-radius",
+		"border-top-right-radius",
+		"border-bottom-right-radius",
+		"border-bottom-left-radius",
+		"border-image",
+		"border-image-source",
+		"border-image-slice",
+		"border-image-width",
+		"border-image-outset",
+		"border-image-repeat",
+		"outline",
+		"outline-width",
+		"outline-style",
+		"outline-color",
+		"outline-offset",
+		"box-shadow",
+		"opacity",
+		"-ms-interpolation-mode",
+		"transition",
+		"transition-delay",
+		"transition-timing-function",
+		"transition-duration",
+		"transition-property",
+		"transform",
+		"transform-origin",
+		"animation",
+		"animation-name",
+		"animation-duration",
+		"animation-play-state",
+		"animation-timing-function",
+		"animation-delay",
+		"animation-iteration-count",
+		"animation-direction"
+	  ],
+	  "block-opening-brace-space-before": "always",
+	  "declaration-block-trailing-semicolon": "always",
+	  "declaration-colon-space-after": "always",
+	  "declaration-colon-space-before": "never",
+	  "function-parentheses-space-inside": "never",
+	  "function-url-no-scheme-relative": true,
+	  "function-url-quotes": "always",
+	  "length-zero-no-unit": true,
+	  "no-eol-whitespace": true,
+	  "number-no-trailing-zeros": true,
+	  "property-no-unknown": true,
+	  "property-no-vendor-prefix": true,
+	  "scss/dollar-variable-colon-space-before": "never",
+	  "scss/selector-no-redundant-nesting-selector": true,
+	  "selector-pseudo-class-parentheses-space-inside": "never",
+	  "shorthand-property-no-redundant-values": true,
+	  "string-quotes": "double",
+	  "unit-allowed-list": [
+		"ch",
+		"em",
+		"ex",
+		"rem",
+		"cm",
+		"in",
+		"mm",
+		"pc",
+		"pt",
+		"px",
+		"q",
+		"vh",
+		"vw",
+		"vmin",
+		"vmax",
+		"fr",
+		"deg",
+		"grad",
+		"rad",
+		"turn",
+		"ms",
+		"s",
+		"Hz",
+		"kHz",
+		"dpi",
+		"dpcm",
+		"dppx",
+		"%"
+	  ],
+	  "value-no-vendor-prefix": true
+	}
+  }