Reduce image size

[tfausak]

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[tfausak]

Stack was only installed to avoid having HLS prompt to install it. We don't actually use Stack and I would prefer to not install it at all in order to avoid confusion.

HLS roughly doubles the size of the image, from 2.4 GB to 4.5 GB. I would prefer this image to be relatively slim, then other images can layer things on top.

I removed GHC's documentation, since I don't think anyone will be looking at that inside the container.

I also removed support for profiling builds. This hurts a bit more, but it's a huge amount of space for something that isn't used that often.

Finally I made some updates to the build process. Now images are tagged with GHC_VERSION-COMMIT_SHA, rather than sha-COMMIT_SHA like before. Also this now builds for both GHC 9.0.2 and 9.2.4. And finally it uses a cache to make builds much faster in the common case.

The last thing I need to do here is actually fill out the README.