chore: drop deprecated options related to CIBW_ENABLE

[mayeut]

Drop deprecated options related to CIBW_ENABLE.

based on #1912

[mayeut]

Should we be keeping the command line option but turn it in an enable in options.py ?

[henryiii]

Should we instead support --enable=<opt> --enable=<opt>? We also now have --only, which you can use to build a pre-release wheel, so maybe we don't need a CLI option for this anymore? (It also is supported statically now)

[mayeut]

Only a few projects are using this in their CI and those could probably move to the static definition (despite our recommendation not to deliver wheels in pre-ABI stability, for now at least).

I liked --prerelease-pythons better than --only because it allows to check musl/glibc, gil/no-gil and multiple architectures in just one pass.

For UNIX users debugging locally, CIBW_ENABLE=cpython-prerelease cibuildwheel ... works quite easily so probably not worth adding an --enable flag. It might be a bit more painful on Windows if you don't want to leave the environment variable after execution (don't know if there's a one liner there) but we can still probably live without a new option as well.

So, maybe just remove the option for now ?

[henryiii]

I'd be okay with that.

[joerick]

I'd be in favour of a --enable= command line option, because the ergonomics make sense to me - you could do one cibuildwheel execution for the PyPI artifacts, then another with experimental stuff enabled, that might go to a different place.

[joerick]

I pushed a commit to add the enable cmdline option.