chore(lint): setup `eslint-config-flat-gitignore` #2265

Job	Run time
Lint	47s
Test (lts/*)	2m 7s
Test (20)	2m 6s
Test (18)	2m 15s
Test with typescript-eslint v7	2m 8s
Test without ESLint Stylistic	2m 17s
Test with ESLint v8	2m 19s
Test (21)	2m 7s
Test with old ESLint Stylistic (3)	2m 13s
Test with old ESLint Stylistic (4)	2m 13s
Test with old ESLint Stylistic (2)	2m 8s
	22m 40s

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