Add ability to mark a multibranch pipeline as a favourite - NOT a branch

I have a multibranch pipeline that contains only GitHub Pull Requests — no branches.

I would like to be able to mark the whole pipeline folder as a favourite — I'm not interested in any one particular branch (PR), as these are pretty much ephemeral.

i.e. it's probably just a shortcut to the pipeline folder, but since it's one of my most-used pipeline folders, I'd like to have it at the top of my dashboard.