feat: introduce `tsdown`, support mixed js & ts in codebase #2198

Job	Run time
Test without ESLint Stylistic	2m 13s
Lint	51s
Test (20)	1m 2s
Test with ESLint v8	48s
Test with old ESLint Stylistic (2)	2m 11s
Test (21)	47s
Test (18)	46s
Test (lts/*)	59s
Test with old ESLint Stylistic (3)	2m 8s
Test with typescript-eslint v7	2m 13s
Test with old ESLint Stylistic (4)	2m 9s
	16m 7s

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