InlineEdit: Allow to upload change edit with git push

Edits can already be pulled with download commands. This change allows
edit to be pushed to gerrit by using magic branch %edit option.

Change must already exist for edit to be created/replaced. One use case
where edit might need to be replaced with git operations is rebasing of
edits on new patch set, in which case two refs are affected: old ref is
deleted and new ref is created:

  $ git push g HEAD:refs/for/master%e
  Counting objects: 14, done.
  [...]
  remote: Processing changes: updated: 1, refs: 2, done
  remote:
  remote: Updated Changes:
  remote:   http://localhost:8080/42 Fix typo in the doc [EDIT]

Change-Id: I3dbf66f1700c212ab90acfa77a5bd1e774b94555
5 files changed