Distinguish active branches from stale branches

[jpraet]

Feature Description

Currently the gitea branch list view shows the default branch, followed by a paginated list of all other branches sorted alphabetically.

This view is hard to navigate if you have a lot of branches. It would be better to distinguish the active branches from the stale branches, as also done on github. I also think it makes more sense to sort them by descending latest modification date, as users are generally more likely to be looking for those recently updated branches.

Screenshots

[jpraet]

Relates to #12763

[lunny]

related to #22743 and we need to know what's the stale's definition. 1 year ago branches should be considered as stale?

[lunny]

Branches are currently sorted by their latest update time. If we define active and stale based on the last updated time, would that be sufficient?

[jpraet]

For reference, on GitHub: https://docs.github.com/en/repositories/configuring-branches-and-merges-in-your-repository/managing-branches-in-your-repository/viewing-branches-in-your-repository

Stale branches: The Stale view shows all branches that no one has committed to in the last three months, ordered by the branches with the oldest commits first.