This adds an extra step definition which can push the result of
running a josh filter on the repository to Github.
Change-Id: I1f93ae78e1bf452fbd1b21ce943a60acc85c944f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5666
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
Reviewed-by: grfn <grfn@gws.fyi>