Synchronize common repo files across `reactive-python`

[Archmonger]

Current Situation

Currently, our repos get basic configuration files out of sync from each other.

Proposed Changes

Synchronize common files (pre-commit-config.yaml, license, code of conduct, contributing, .vscode, .github) via GH actions.

Implementation Details

I recommend using the repo-file-sync GitHub action to automate standardized configurations across reactive-python repos.

That's what we use at Jazzband alongside our template repository.