Display post receive warnings from Rails
This MR allows for Rails to send warnings to gitlab-shell to be displayed to the user.
In particular, this will allow us to display warnings due to issues with processing push options https://gitlab.com/gitlab-org/gitlab-ce/issues/43263 and https://gitlab.com/gitlab-org/gitlab-ce/issues/53198.
The warnings are printed using the existing print_broadcast_message
method, prefixed with a heading, to ensure that all warnings are formatted correctly:
remote: ========================================================================
remote:
remote: WARNINGS:
remote: Could not handle push options 'merge_request.cdreate': Push options
remote: are not valid
remote:
remote: ========================================================================
Warnings will be the last messages to display.
Edited by Luke Duncalfe