Add support for Android Gradle plugin 8.2

[mhsmith]

See checklist in product/gradle-plugin/README.md.

RC was released yesterday, so we should test against that before releasing 15.0, but we shouldn't wait for the stable release because we've delayed KTS support too long already. 15.1 won't be too far away anyway.

[lumstep]

Is there any possibility to use a RC?

[mhsmith]

As far as I know, the Chaquopy 15.0.0 pre-release at #934 (comment) will also work with Android Gradle plugin 8.2. If you have any issues, please post them below.

[mhsmith]

All tests passing with version 8.2.0-rc03. I'll leave this issue open until the stable release, at which time the checklist can be completed.

The GitHub issue templates should also be updated to refer to the chaquopy section as well as the python section.