Partial fix to #44378

These can be a `BatchLoader` which is proxying a nil, while not being concrete
nils themselves.

and fixes the project description not being imported

Closes #31114.

These extra sort keys caused sequential scans on the namespaces and projects
page. Removing them makes the page load on GitLab.com.

Closes #44338

[ci skip]

Closes #43355

This is most a backport of
https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/4987/diffs but includes
other columns that use column_exists? in a way that may cause unnecessary
schema loads.

Carried over from https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/8857

Previously, we kept them all in the cache. We don't need the highlight results
for older diffs - if someone does view that (which is rare), we can do the
highlighting on the fly.

Updates Files::MultiService for the commits API which is in turn used by the
multi-file upload web UI

Ensures that files which should be in LFS are transformed into LFS pointers
Uses Lfs::Transformer which then links LfsObjectProjects on success

When importing from a GitLab archive, an admin can carry over the
assignations. Other users can not.

When a regular user is importing an issue with multiple assignees, the
assignee is replaced with the current user, meaning we would try to
insert current user as an assignee multiple times.

By filtering the array before storing it, the import becomes more
robust.

The same as the SQL queries, show the details of Gitaly calls in the performance
bar, as a modal that can be opened in the same way.

Also use Gitlab::Auth::OAuth::Provider.config_for to access OmniAuth config

When https is configured in the URL, also use that, and do not set it
to http.

Closes gitlab-org/gitlab-ee#5217

Previously, we only handled non-ASCII file contents, but the name itself can be
non-ASCII.

Fixes #40620,#33678

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/44024

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/4281