Improve 'Remove Branch' button workflow

[d-gs]

Feature request

Expected Behavior - What were you expecting to happen?

Remove Branch button should be enabled for existing branches (not default ones), without checkout to another branch beforehand.

Current Behavior - What happens?

The deletion of branches in the UI currently requires:

1. Have a clean worktree (to allow checkout)
2. Checkout a different branch
3. Select (without checkout) branch to delete
4. Use the Remove Branch button (inactive until now)

Possible Solution

Remove Branch button should checkout the default branch if it is the current branch. This requires a decision of what to do with "dirty" worktrees, so a popup to the user should be shown ask if everything should be deleted or if they want to abort the deletion.

Context

User experience.

Notes and further information

None