perf(richtext-lexical): fix all eslint errors to get react compiler running on all files, enable strict: true

[AlessioGr]

This PR fixes all eslint errors in the richtext-lexical package. This includes all eslint errors of the react compiler.

Since the react compiler skips files that have react compiler eslint errors, this PR will make it run on files it previously ignored.

Source: https://react.dev/learn/react-compiler#installing-eslint-plugin-react-compiler

The ESLint plugin will display any violations of the rules of React in your editor. When it does this, it means that the compiler has skipped over optimizing that component or hook. This is perfectly okay, and the compiler can recover and continue optimizing other components in your codebase.

This PR also enables strict: true. Thanks to @GermanJablo for doing most of the work by enabling noImplicitAny and strictNullChecks in previous PRs