Allow pushing branches and tags to customer git repos

Allow pushing branches and tags to customer git repos

For pipelines in the private repository, add an optional manual job,
which allows the current branch to be pushed into the specified
customer's git repository. This can be useful to provide patch previews
for early testing.

For tags created in a private repository, add a manual job which pushes
the created tag to all entitled customers.

(cherry picked from commit 378b412e94a40ee74ab5c9edfb3a2059612a59ff)