Generate GitHub Actions CI Jobs automatically

[rnorth]

Generate GitHub Actions CI jobs for modules
Refs #2177, #1836

PR 1 of 2: this PR includes a script for generating the CI job configuration, but the script has to be manually run
A future PR should run the generation script automatically as a separate Action and commit changes, so that no manual updates are needed

[bsideup]

I wonder if shared compile (1 busy worker) actually helps. Have you done some measurements yet?

[rnorth]

It does not, so I removed it 😄

[rnorth]

Indicative timings:

A fully cached (S3 remote build cache) build: 6m25s

A completely uncached build (with --no-build-cache): 19m56s

For the uncached build, the longest job, and therefore bottleneck is jdbc-test. The core module is approx 14mins.

Therefore I think we could reduce the max build time to ~14mins by splitting up the JDBC testing for each DB into the relevant modules, to take advantage of parallelisation.

Further performance gains could be possible by splitting up the core job, but that may take more effort.

[rnorth]

The up-to-date awareness makes this vastly better!

Let's 🚢 !