Fix Linter type import in index.d.ts

[ocavue]

Thanks for adding TypeScript declarations in the latest v9.29.0.

I found an issue when using the new declaration. In the lib/index.d.ts, the Linter namespace is pointing to typings/eslint/index.d.ts. However, typings/ is not included in the final NPM package, therefore the declarations in index.d.ts is not working.

This issue can be fixed by adding a single line import type { Linter } from 'eslint' as shown in this PR.

Other code-styling changes included in this PR are made by Prettier based on eslint-plugin-vue's Prettier config.

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Just FYI, the latest eslint has already includes TypeScript declarations, which means you don't need @types/eslint and perhaps also typings/eslint/index.d.ts anymore once eslint-plugin-vue updated to the latest version of eslint (currently eslint-plugin-vue is still using eslint@8).

[FloEdelmann]

Thanks, this looks good!

Also, given there is already a duplicate PR (#2575), this seems to fix the issue for others as well.