ICU-23270 ICU4J Maven improvements

[mihnita]

Checklist

• Required: Issue filed: ICU-23270
• Required: The PR title must be prefixed with a JIRA Issue number. Example: "ICU-NNNNN Fix xyz"
• Required: Each commit message must be prefixed with a JIRA Issue number. Example: "ICU-NNNNN Fix xyz"
• Issue accepted (done by Technical Committee after discussion)
• Tests included, if applicable
• API docs and/or User Guide docs changed or added, if applicable
• Approver: Feel free to merge on my behalf

[mihnita]

Not yet ready, I will add fixes and will do heavy testing.
But if you want a head-start, I don't plan to touch the existing commits anymore.
Only add on top of them, and (likely) squash all the "churn" added in to a final "Cleanup" commit

[mihnita]

Still to do: CI, update doc, testing (lots of it!)

[jira-pull-request-webhook]

Notice: the branch changed across the force-push!

• icu4j/releases_tools/shared.sh is now changed in the branch

View Diff Across Force-Push

~ Your Friendly Jira-GitHub PR Checker Bot

[mihnita]

Ready for review

[echeran]

LGTM

[mihnita]

Thank you very much!

[mihnita]

Do you want me to squash?

[jira-pull-request-webhook]

Hooray! The files in the branch are the same across the force-push. 😃

~ Your Friendly Jira-GitHub PR Checker Bot