Gitaly Server info for admin panel

See merge request gitlab-org/gitlab-ce!16794

Implements the client side for gitlab-org/gitaly#819. Which is a server
info command. This checks the server version and git binairy version on
the server.

A small UI was added for administrators, so they can check the status of
the Gitaly server. This is done for each storage the monolith knows.

Because of this commit, gitlab-org/gitlab-ce!15580 is now closed. That
MR removed the Git version too, but didn't replace it with anything.

The group activity feed was limited to the first 20 projects found
in the group, which caused activity from some projects to be omitted.
A limit of 20 is applied to the query for events, so the
extra pagination does little in the way of performance.

Closes #42560

On epics roadmap page we list all epics in the given time frame
without pagination (at least for the first iteration), in this
case it would be nice to use the existing issuables index logic
except pagination (see MR gitlab-ee!4281). For this reason this
patch allows to easily disable pagination.

Related gitlab-ee!4281

This will enable Geo to skip shards that not operational.

Relates to gitlab-org/gitlab-ee#4329

The default 404 handler would return the Content-Type format based on the
given format extension. This would cause the Rails CSRF protection to flag an
error, since the .js extension gets mapped to text/javascript format.

Closes #40771

When searching we would limit the scope of ancestors to load because
the filter would be applied to the ancestors. Instead, we need to load
_all_ ancestors for matching projects.

Resolve "New user is sent back to Register tab after confirming email"

Closes #41206

See merge request gitlab-org/gitlab-ce!16174