ICU-22606 Create an (almost) full release from CI

[mihnita]

Automates most of the tasks required for release.

There is no need to build on Windows / Ubuntu / Fedora, there (almost) no need to upload files by hand to the GitHub Release, there is no need for PGP signing, keys, etc.

Not final, close enough.

Checklist

• Required: Issue filed: https://unicode-org.atlassian.net/browse/ICU-22606
• Required: The PR title must be prefixed with a JIRA Issue number. Example: "ICU-1234 Fix xyz"
• Required: The PR description must include the link to the Jira Issue, for example by completing the URL in the first checklist item
• Required: Each commit message must be prefixed with a JIRA Issue number. Example: "ICU-1234 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

ALLOW_MANY_COMMITS=true

[jira-pull-request-webhook]

Notice: the branch changed across the force-push!

• docs/processes/release/tasks/publish/release.md is different

View Diff Across Force-Push

~ Your Friendly Jira-GitHub PR Checker Bot

[markusicu]

rslgtm -- I might not be the best person to review this.
@echeran @rp9-next @richgillam @srl295 @yumaoka FYI

[mihnita]

I've improved the doc a bit. I will squash at the end if you want.

[echeran]

LGTM

[mihnita]

Thank you all!

I am happy to improve the doc / anything else.
But at least we now have in place everthing we need for the release.

[mohd-akram]

Putting a README file in the .github directory seems to cause it to be displayed on the project page (instead of the README file in the root directory).