Adds GitHub action CI workflow

[SHession]

What does this change?

This PR attempts to move our CI away from TeamCity and into GitHub actions using the latest tools from DevX.

NB The action will run for the PR but will not attempt to upload until we add riffRaffUpload to the sbt step.

How to test

We will need to pause TC build and set the build number, we should then be able to test the process end-to-end using CODE.

How can we measure success?

We move away from TeamCity builds and gain all the benefits of GitHub actions!

Have we considered potential risks?

This could be disruptive for Atom Workshop builds.

[SHession]

@akash1810, it looks like from a cold box the build times are quite similar between TC and GHA but they can be significantly quicker in TeamCity if it's warm. Any thoughts:

[akash1810]

@akash1810, it looks like from a cold box the build times are quite similar between TC and GHA but they can be significantly quicker in TeamCity if it's warm. Any thoughts:

An initial glance suggests a lot of the time in GHA is spent downloading dependencies. Caching these should help:

• Node caching https://github.com/actions/setup-node#caching-packages-dependencies
• SBT cache https://github.com/actions/setup-java#caching-packages-dependencies

I've not actually done SBT caching yet, so intrigued to know how to!

There's a fair amount of boilerplate here. If you're interested, we can discuss some composite actions we're creating to simplify this file?

[SHession]

@akash1810, thanks for the review, really helpful. I've got it working now and have successfully deployed to CODE. Happy to discuss any other suggestion for improvements but possibly we could iterate on them in another PR?

I've added SBT caching which seems to have improved the build times somewhat. I haven't yet added yarn caching, might improve build speeds a bit more.

[akash1810]

YEAH! Great work!

update: was hoping that gif would be bigger/better...

[akash1810]

I've added SBT caching which seems to have improved the build times somewhat. I haven't yet added yarn caching, might improve build speeds a bit more.

I think yarn caching is provided for free if when the lockfile is on the root of the repo, which it is.