Heads up: gradle build changes on main

For those who don't track PRs so closely, this one introduces significant
changes to the gradle part of the build -

https://github.com/apache/lucene/pull/14764

It isn't all sweet and I've tried to test it as well as I could but it's a
rather large and complex build file so things may break. I would like to
commit this to main so that I can work on further cleanups and improvements
that are more fine-grained.

If there are no objections, I will do this tomorrow so that I can monitor
and fix the builds over the weekend.

If you see something awkward or *not* working, please let me know (mailing
list or github issue would be fine).

Dawid