Compile casacore in dockerfile instead of installing python-casacore through...

Compile casacore in dockerfile instead of installing python-casacore through pip. This way we can use the latest version of casacore, since pip's python-casacore is often behind.

I added a test_build step we can use to run a weekly or so build test.

I ran the job manually here: https://git.astron.nl/ldv/imaging_compress_pipeline/-/pipelines/107959

Update: new manual job here: https://git.astron.nl/ldv/imaging_compress_pipeline/-/jobs/1021270