Remove compiled JS content

[stuartleeks]

Closes #209

I explored https://github.com/JasonEtco/build-and-tag-action as referenced in #209, but the expectations didn't align with the structure in this repo (e.g. we have a run-main.js and run-post.js that we need to preserve rather than a single file)

In the end, I took the following steps:

• remove the compiled code and add these folders to .gitignore
• update the GH workflows that use the action in PR tests to compile the JS code before running
• update the release flow to create a temporary branch with only the files needed for running the action, create a tag + release with the full version number, and push to the major.minor tag version
• bumped the version from 0.2.x to 0.3.x. This prevents anyone referencing 0.2 (as per the docs) from picking this up until better validated - a future PR will update the docs

[stuartleeks]

Successful PR build via ci_branch: https://github.com/devcontainers/ci/actions/runs/4242931637

[stuartleeks]

Re-ran the branch-based build to test workflow changes: https://github.com/devcontainers/ci/actions/runs/4254367522 ✅