Add Prettier

[koesie10]

This adds Prettier and replaces tsfmt. VSCode is set to use Prettier for formatting TypeScript/TSX files and format on save since Prettier is very fast and does not cause any noticeable delay.

I've changed some of the default configuration of Prettier so we have less changes, but there are still many changes in formatting in almost all files. It's best to review this PR commit-by-commit: the second commit just runs npm run format and does not have any manual changes.

Checklist

• [ ] CHANGELOG.md has been updated to incorporate all user visible changes made by this pull request.
• [ ] Issues have been created for any UI or other user-facing changes made by this pull request.
• [ ] [Maintainers only] If this pull request makes user-facing changes that require documentation changes, open a corresponding docs pull request in the github/codeql repo and add the ready-for-doc-review label there.