Migrate Eclipse Orbit from Gerrit to GitHub

@webmaster Can we schedule the migration of Orbit (https://git.eclipse.org/r/admin/repos/orbit/orbit-recipes,general) to GitHub for just after the 2023-03 simrel please.

The week of March 20th or March 27th would be great.

Can we make the repo on GitHub be https://github.com/eclipse/orbit?

I have sent a request for comment to the orbit-dev mailing list and will update in case anyone has strong objection to this timing.