Improve changing remotes

[schmoelder]

When updating tests, I had to migrate RDM studies from @ronald-jaepel's private namespace to the IBG-1/ModSim/cadet namespace. Changing the git remotes (both of the project and output repo) was quite painful. 😓

To be honest, we could also reconsider the initialization. Currently, the initial commit adds a lot of stuff which is not necessarily in great shape (e.g. the README). Do we even need that? I mean, it's nice to have an automatic link to the output repo but since it often does not work out of the box, I would rather not have this "feature".

[ronald-jaepel]

Sorry to hear you found it painful.

For future reference and as a possible starting point for the migrate function:

There's the repo.check() function that's also available in the CLI as rdm check. It confirms a consistent internal state, including the remotes, and it updates the links in the README. As far as I recall Katha and I had used it when migrating some of her example cases and back then it worked. No guarantees it still works.

So to change remotes, the workflow is:

1. rdm clone
2. git remote set-url origin <>
3. git -C output set-url origin <>
4. rdm check
5. rdm push

And that should update the remotes, update the info in the cadet-rdm metadata file (forgot the name) and update the links in the READMEs.