github actions: cache deps, run nightly test

[ryanio]

Adds caching of node_modules for faster gh action runs.

See how a cache hit looks here.

Note: we don't have a package-lock.json file in this repository so I am hashing package.json as the cache key instead (also what happens in current .circleci). @alcuadrado likes not having a package-lock.json "as it forces us and the CI to experience the libraries as users would."

@evertonfraga suggested we run a nightly job without caching to catch any potential issues that may happen when an in-range dependency update breaks the build or tests, so I added vm-nightly-test.yml that runs without any caching.

Also accidentally missed running gh actions on pull_request so this PR includes that.

[github-actions]

Coverage remained the same at 95.41% when pulling 4900853 on actions-cacheDeps into 0fc97b4 on master.

[evertonfraga]

Everything in the vm-test.yml looks good!

@ryanio would you please add cache to the Coverage and Lint jobs as well?

[ryanio]

oops accidentally committed some residual test files for the PR labeler so that's why the labels got added.

@ryanio would you please add cache to the Coverage and Lint jobs as well?

done!

[holgerd77]

Thanks Ryan, great work! Also had a short look, change requests from @evertonfraga have been addressed so I think this should be ready for merge.

I think we might now also be ready here to also remove the CircleCI support along one of the next PRs? Will move the requirement checks from Circle to Actions after this post.

Will dismiss, changes addressed.

[evertonfraga]

oops accidentally committed some residual test files for the PR labeler so that's why the labels got added.

@ryanio that was me! I created the labels manually, so we have one more item crossed for the migration.

[evertonfraga]

The nightly test successfully ran tonight.

🎉 @ryanio

[holgerd77]

Nice