refactor: migrate addon package to TypeScript #489

Job	Run time
Lint	35s
Tests (ubuntu-latest, chrome)	33s
Floating Dependencies (ubuntu-latest, chrome)	45s
Type checking - [email protected]	31s
Tests - ember-lts-3.28	52s
Type checking - [email protected]	35s
Tests - ember-lts-4.4	48s
Type checking - typescript@next	36s
Tests - ember-lts-4.8	55s
Tests - ember-lts-4.12	51s
Tests - ember-classic	59s
Tests - ember-release	56s
Tests - ember-beta	59s
Tests - embroider-safe	59s
Tests - embroider-optimized	54s
Tests - ember-canary	54s
	12m 42s

Provide feedback