chore: introduce `@eslint/markdown` and `eslint-plugin-markdown-preferences` #2072

Job	Run time
Test (18)	2m 13s
Lint	54s
Test (20)	2m 11s
Test with old ESLint Stylistic (3)	2m 13s
Test (21)	2m 6s
Test with old ESLint Stylistic (4)	2m 13s
Test (lts/*)	2m 17s
Test with typescript-eslint v7	2m 11s
Test with ESLint v8	2m 17s
Test without ESLint Stylistic	2m 7s
Test with old ESLint Stylistic (2)	2m 14s
Test (18)	2m 20s
Test (20)	2m 10s
Test (lts/*)	2m 10s
Test (21)	2m 8s
Test with typescript-eslint v7	2m 11s
Test without ESLint Stylistic	2m 7s
Test with old ESLint Stylistic (2)	2m 14s
Lint	54s
Test with ESLint v8	2m 17s
Test with old ESLint Stylistic (4)	2m 13s
Test with old ESLint Stylistic (3)	2m 13s
	45m 53s

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