Add JS code linting as GH action workflow

[mateusz1913]

We already use eslint and typescript as a pre-commit git hook. Next step should be to run it on CI for pull requests, similar to how it should be done for native linters

• The workflow should be run whenever the pull request changes any JS/TS file in packages/react-native-legal workspace
• let's use ubuntu-latest as a runner (no need for macos)
• eslint and typescript will require node_modules to be installed (unlike for native linters) so let's use actions/cache to speed up subsequent node_modules installs
• for node_modules installation and running some nodejs scripts, let's use actions/setup-node with cache options