[Release] Add support for releasing .jar including JNI binaries

[kou]

Describe the enhancement requested

This is a follow-up task of GH-20/GH-496.

See also: #496 (comment)

[kou]

I considered how to implement this.

There is a suggestion that we can use reusable workflow. But I want to merge test_jni.yml to rc.yml because I want to use source archive used for RC.

If we use the source archive used for RC and we're ready for Reproducible Builds, we'll be able to sign automatically.
See also: https://infra.apache.org/release-signing.html#automated-release-signing

@lidavidm What do you think about this idea?

[lidavidm]

I guess we're running rc.yml on PRs too so we're still getting testing. So it's fine by me!

[kou]

I guess we're running rc.yml on PRs too so we're still getting testing.

Correct!

So it's fine by me!

Thanks!