Revert 09c36781 & tweak linting (#1501)

This diff reverts 09c36781 and tweaks how some of our linting was
working.

I'm not actually sure what caused the regression that 09c36781 was
fixing - it was something to do with typescript being used to transpile
eslintrc.js, but that being excluded from the tsconfig for those
projects. I fixed that by removing `rootDir` from those, but that
revealed some other issues with files not getting ignored correctly.

I fixed the ignoring issue with a change I've wanted to make to these
scripts for a while: only running them on files that are actually
tracked by git, instead of on everything with a relevant extension. A
side effect of that is that we have to re-implement .eslintignore
support ourselves, but that's very straight forward: the `ignore`
package that eslint uses is very easy to include.

### Change Type
- [x] `internal` — Any other changes that don't affect the published
package (will not publish a new version)

### Test Plan
-

### Release Notes
[internal-only]

scripts/check-scripts.ts

@@ -63,14 +63,6 @@ const perPackageExceptions: Record<string, Record<string, () => string | undefin
 		prepack: () => undefined,
 		postpack: () => undefined,
 	},
-	'tldraw-vscode': {
-		lint: () =>
-			'yarn run -T eslint --report-unused-disable-directives --ignore-path ../../../.eslintignore',
-	},
-	'@tldraw/vscode-editor': {
-		lint: () =>
-			'yarn run -T eslint --report-unused-disable-directives --ignore-path ../../../.eslintignore',
-	},
 }
 
 async function main({ fix }: { fix?: boolean }) {