Introduce the parallel orchestration framework for `repo sync
--interleaved`.
The new logic respects project dependencies by processing them in
hierarchical levels. Projects sharing a git object directory are grouped
and processed serially. Also reuse the familiar fetch progress bar UX.
Bug: 421935613
Change-Id: Ia388a231fa96b3220e343f952f07021bc9817d19
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/483281
Commit-Queue: Gavin Mak <gavinmak@google.com>
Tested-by: Gavin Mak <gavinmak@google.com>
Reviewed-by: Scott Lee <ddoman@google.com>
b4b323a8bd