Gitlab: creating a new folder structure from the plugin doesn't work.

[rbosker]

Describe the bug

• ❌Gitlab: creating a new folder structure from the plugin doesn't work.
• ✅ connecting to an existing folder works
• ✅ creating and syncing to a single file works

To Reproduce
Steps to reproduce the behavior:

1. Setup Gitlab
2. Use as path a folder that doesn't exist
3. You will get a 404 and the folder isn't created.
   

Acceptance criteria

• Users should be able to push to a new branch when editing the sync provider details (i.e. from main to new-branch)
• New branch created should be based on the current one that's selected in the plugin
• New branch created should be selected and visible in the branch switcher
• Users should be able to push to a single new file or a new folder when editing the sync provider details (i.e. change from tokens.json to theme)
• If the user does not complete the "Push to remote" flow, the sync provider details should revert to the original ones

[cuserox]

👋 @rbosker the fix is ready to be reviewed (🔨 while I update tests) - #3089 🙏

[cuserox]

This has now been merged to the main branch 🎉