Repo Transition to GitLab

[Chris Johns]

Hi RTEMS Community

The git repos on git.rtems.org are open and accepting patches. The GitLab repos
will move us to main, something we have been waiting to do. Allowing commits
into the repos means they will be brought across and played on top of the new
main branch. We have changes in the repo on GitLab as part of our testing and
new files such as CODEOWNERS.

As a result you will check out main and not rename your master to main.

Regards
Chris
RTEMS GitLab Team