Default to ESLint's `root: true` to match TSLint behavior

[hyperupcall]

🚀 Feature Request

To the best of my knowledge, tslint does not automatically search for and process tslint.json files that are in parent directories. ESLint does this by default, and needs to be disabled by specifying root: true at the configuration top-level. To match the default behavior of tslint, we could set this ESLint top-level property

If this feature request is accepted, I am able to make a PR

I can make a PR

Existing Behavior

Does not set root property of ESLint configuration

Change Proposal

Set top-level root to true in all generated configs

[JoshuaKGoldberg]

That makes sense, good point! https://typescript-eslint.io/docs/linting also recommends setting root: true.