Add ListRef RPC to list all refs
To create an incremental backup using git bundle create we want to be able to pass a list of ref patterns that ensure the bundle mostly only contains the new objects since the last backup. To do this we cannot rely on git bundle list-heads since this would require downloading bundles from object storage. Instead we're going to separately fetch the entire ref list every time a backup is taken (full or incremental) then use the previous list and the current list to calculate the required ref patterns for git bundle create.
Edited by James Fargher