Adds compress-level option to sdist and wheel configs

[cstigen]

We're using hatchling at work to bundle ~80 moderately large JSON files into an sdist tarball.

This takes ~50 seconds with the default gzip compression level of 9. With level 1 it takes only a few seconds at the expense of a few tens of megabytes. For us, this is a desirable trade-off, and I believe it could make sense for others as well.

Since I wasn't able to find any contribution docs I'm going to put this PR in draft mode. For example, I haven't made any tests.

Of course, I'm expecting some feedback on the merit of this idea as well.