Closes #38741

* 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

Navigating to the "Members" section of a project would omit the
relative URL root path. Fix the redirection and eliminate the
need for a redirection in the first place.

Fix other redirections failing to work with relative roots

Because container registry tags can have periods, the addition of the `.json`
format caused ambiguity. Since the tag name regex is greedy, it would attempt
to locate an image named `foo.json` instead of `foo`.

Closes #39260

Because container registry tags can have periods, the addition of the `.json`
format caused ambiguity. Since the tag name regex is greedy, it would attempt
to locate an image named `foo.json` instead of `foo`.

Closes #39260

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/34261

First commit in probably 2, for resolve gitlab-org/gitlab-ce#15582. This
commit is renaming files and classes from build to pipeline. Also
wording is editted to pipeline. Given `pipeline` had more characters
than `build`, I've made the field a bit wider. The width now matchers
the one for the coverage badge, so they look nice when in a table
format, or in a list.

As soon as this commit is merged to master, and released, the build.svg
is deprecated, meaning that all users which already placed a badge
should update it. However, to make sure it keeps working tests are added
for this case.

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/11407#note_30922591

The decision was made around:
https://gitlab.com/gitlab-org/gitlab-ce/issues/26407#note_30624641

Additional metrics initial work, with working metrics listing, but without actoual metrics mesurements