Add force option to UserCommitFilesRequestHeader
This option will be used by clients to send an RPC call with the force
option.
Issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/45035
gitaly MR: gitaly!1077 (merged)
gitlab-rails MR: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/25286
Edited by Patrick Bajao