Try ftp.rtems.org first to download files before anywhere else

Summary

We should set the RSB to use ftp.rtems.org first before anywhere else. Reasons:

• Right now *.gnu.org is dead so the RSB sits and waits.
• It will be faster for most people but also consistent speeds.
• The chance of something breaking is lower from changing URLs or remotely deleted files

If we start with RTEMS 6 we can have a subdirectory and do that going forward. Any versions before that can use the old system just fine but we should still have an archive of all files just in case the older ones go away which they usually do, eventually.

This includes patches -- literally all the files. It will solve the issue of older branches breaking when we move repositories around. We've already spoken about a 'legacy' archive. GitLab does automatically put redirects in but that is not guaranteed to always exist there are cases where they get removed.

We'll be able to support old branches with no extra work using this method.

These will also break the next time we change platforms staying on GitLab forever would be great but we don't know what the future entails ftp.rtems.org will always be ours to use and in our control.