refactor: migrate addon package to TypeScript #491

Job	Run time
Lint	30s
Tests (ubuntu-latest, chrome)	37s
Floating Dependencies (ubuntu-latest, chrome)	47s
Type checking - [email protected]	30s
Tests - ember-lts-3.28	1m 3s
Tests - ember-lts-4.4	54s
Tests - ember-lts-4.8	52s
Type checking - [email protected]	35s
Tests - ember-lts-4.12	57s
Type checking - typescript@next	30s
Tests - ember-classic	45s
Tests - ember-release	57s
Tests - ember-beta	46s
Tests - embroider-safe	49s
Tests - embroider-optimized	57s
Tests - ember-canary	48s
	12m 17s

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