project setup is broken

[timostamm]

Noticed several issues when looking into dependabot PRs:

• This project has a lint script, and has four dependencies related to eslint, but no eslint configuration file. Running npm run lint fails with an error message.
• The project has a format script depends on prettier, but running the script produces 85 changed files. We should either remove prettier altogether, or make it part of CI.
• The project has a script check:types that does not run in CI, and fails with error about broken imports related to prism-react-renderer, possibly introduced by https://github.com/bufbuild/connect-docs/pull/383. I am unsure whether this is a bug.
• The project has a prose script and depends on vale, a prose style checker. Running the script errors, there is no vale config.

I suggest we remove lint, format, and prose, and all their dependencies.

From what I see, npm run build does no type checking - I can successfully run it after putting const x: string = 123 at several places in the code base. I suggest we remove TypeScript from this repo, or fix check:types and run it in CI, so that we also have some static checking for dependabot PRs.

[timostamm]

(originally filed in the wrong repo in https://github.com/bufbuild/connect-docs/issues/421)