Move AJDT to GitHub

This issue can be regarded as a logical continuation of Bugzilla #565452. The AspectJ development team wants to finish transitioning the project's repositories to GitHub. After AspectJ and AspectJ JDT Core were migrated a while ago already, only one Git repository is remaining: AJDT.

Some due diligence issues before moving on with this request: We have Jenkins jobs doing the following, among other things:

• use eclipse-signing-maven-plugin in order to sign artifacts which later are being published on Eclipse P2 update sites
• copy artifacts from the Jenkins instance to the P2 update site server with a command like scp -vr 421 genie.ajdt@projects-storage.eclipse.org:/home/data/httpd/download.eclipse.org/tools/ajdt

So the open questions are:

• Can we use eclipse-signing-maven-plugin in GitHub workflows? If so, how?
• Can we publish built artifacts on projects-storage.eclipse.org or any other suitable server, so that finally Eclipse users can consume the AJDT artifacts from an update site like https://download.eclipse.org/tools/ajdt/421/dev/update? If so, how?

We only wish to proceed with the migration after these issues have been clarified. We can talk about the migration details later. Thank you very much.