This allows users to add patches as attachments to merge request
created via email.
When an email to create a merge request is sent, all the attachments
ending in `.patch` will be applied to the branch specified in the
subject of the email. If the branch did not exist, it will be created
from the HEAD of the repository.
When the patches could not be applied, the error message will be
replied to the user.
The patches can have a maximum combined size of 2MB for now.
Various counters would expose either project names, or full project
paths (e.g. "gitlab-org/gitlab-ce"). This commit changes various places
where we use "add_event" so we no longer expose (potentially) private
information.
This could only be possible for users that can create merge requests
within a project.
So they need to be a allowed to create a branch and create a merge request.
When a merge request is created from email, use message body
as merge request description. If message body is empty then
merge request description is still created from the source
branch commit (if there is only single commit in the merge
request).
If message body is empty and there are multiple commits in
the source branch, then merge request description is left empty.
Closes#40968
* new merge request can be created by sending an email to the specific
email address (similar to creating issues by email)
* for the first iteration, source branch must be specified in the mail
subject, other merge request parameters can not be set yet
* user should enable "Receive notifications about your own activity" in
user settings to receive a notification about created merge request
Part of #32878
GitLab Bot