Support renaming the current default branch to the new name

[eclipse-csi-bot]

In GitLab by @netomi on Jul 14, 2023, 23:47

Currently, when updating the default branch setting of a repo, the new branch must exist for the operation to succeed.
Doing it via the Web UI will actually rename the current default branch to the new name.

We should add support to that also via otterdog, utilizing the api for renaming a branch: https://docs.github.com/en/rest/branches/branches?apiVersion=2022-11-28#rename-a-branch

We could add an additional model only field to enable renaming otherwise, just the default branch setting is updating without renaming.

[eclipse-csi-bot]

In GitLab by @netomi on Oct 21, 2023, 17:12

mentioned in commit d5d1845

[eclipse-csi-bot]

In GitLab by @netomi on Oct 21, 2023, 17:12

Done.