Allow trailing whitespace in diff and markdown files (Shopify#1499)

* Ignore trailing whitespace removal in diff and markdown files

* Delegate whitespace management to editorconfig instead of VS Code

* Follow user defaults on trimTrailingWhitespace and insertFinalNewline

.editorconfig

@@ -13,3 +13,8 @@ trim_trailing_whitespace = true
 # See https://daringfireball.net/projects/markdown/syntax#p
 [*.md]
 trim_trailing_whitespace = false
+
+# Disable trailing whitespace removal in diff files,
+# where whitespace is meaningful
+[*.diff]
+trim_trailing_whitespace = false

.vscode/settings.json

@@ -26,8 +26,6 @@
     "styles/": true,
     "types/": true
   },
-  "files.insertFinalNewline": true,
-  "files.trimTrailingWhitespace": true,
   "javascript.validate.enable": false,
   "jest.autoEnable": false,
   "prettier.eslintIntegration": true,