Provide workarounds for both TS (bad peer-provided types handling) and Glint (mishandling of extensions) issues #796

Job	Run time
Slow tests: defaults with npm	1m 54s
Slow tests: defaults with yarn	1m 40s
Lint JS	18s
Tests: Type Check	17s
Slow tests: defaults with pnpm	1m 19s
Tests (addon-location)	53s
Tests (test-app-location)	48s
Slow tests: typescript with npm	2m 30s
Tests (addon-only)	24s
Slow tests: typescript with yarn	1m 48s
Tests (monorepo with npm)	2m 9s
Slow tests: typescript with pnpm	1m 20s
Tests (monorepo with yarn)	1m 26s
Tests (monorepo with pnpm)	47s
Tests (rollup-build)	1m 5s
Tests (declarations-configuration)	42s
	19m 20s

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