feat(backend): GitLab on-premise support and multilevel URLs, SSH git repos

[mbodmer]

• Add support for on-premise hosted GitLab, not only gitlab.com
• Add support for SSH git repositories -> will be converted to "https" API URL
• Add support for multi level gitlab groups
• Respect upper case PRIVATE-TOKEN header
• Mark PRIVATE-TOKEN header value as sensitive
• fix bug: release-plz release fails when no "-o json" given as argument

[mbodmer]

Sorry, I have made a mess with git. Have now force pushed again and fixed the last clippy warning

[mbodmer]

Would you mind approving the builds? Or is there anything i can do?

[MarcoIeni]

Done! I'll review this asap

[MarcoIeni]

I extracted your fix in #1528 because I wanted to merge it asap, thanks!

[MarcoIeni]

I tested this, and I got the error:

Error: failed to release package

Caused by:
    0: Failed to create release
    1: HTTP status client error (403 Forbidden) for url (https://gitlab.com/api/v4/projects/MarcoIeni%2Fmarco-test-gitlab/releases)

• Is the i%2F correct in the URL?
• Are these instructions accurate?
• Maybe I need to select a different role?

[mbodmer]

yes, the project Name is URL encoded, so 2%F is correct for the "/". Also you have to chose Maintainer role or any role with permission to create MR, for the token.
The instructions still apply, just the role could be mentioned, i made the same mistake first. The error is also not very helpful, but I had no idea how to make it more meaningful.
Thanks for reviewing and testing!

[MarcoIeni]

I'll test again, thanks!
For the error, we could link to the docs if gitlab returns a 403.
Do you mind doing this change and updating the docs? If not, I can do it 👍

[mbodmer]

You seem to have a solution in mind, just go for it