Has been in opt out for 5 months, and within GitLab been in production
for longer than that.

No code needs to be migrated as this is implemented in GoLang over at
Gitaly.

Closes https://gitlab.com/gitlab-org/gitaly/issues/314

Direct disk access is done through Gitaly now, so the legacy path was
deprecated. This path was used in Gitlab::Shell however. This required
the refactoring in this commit.

Added is the removal of direct path access on the project model, as that
lookup wasn't needed anymore is most cases.

Closes https://gitlab.com/gitlab-org/gitaly/issues/1111

* processes any pending records which are not migrated yet
* bumps import_export version because of new commits_count attribute
* removes commits_count fallback method

Signed-off-by: NRémy Coutable <remy@rymai.me>

Moves LDAP to its own controller with tests
Provides path forward for implementing GroupSaml

The execution path wasn't clear from the error, but either way this is a
fix.

Closes gitlab-org/gitaly#1115

Conflicts can be resolved by running
`bundle exec rake gettext:find; git checkout locale/*/gitlab.po`

When a request contains an ETag value in its If-None-Match header, the backend
may send a request ID (from Rack) that does not correspond to a value in Peek's
Redis cache (because we aborted the Rails processing in our ETag middleware).

Because a cached response (304) has to replace the headers with those from the
previous 200 - https://tools.ietf.org/html/rfc7234#section-4.3.4 - we add a
custom header that will only be present in cache hits, that can tell the
frontend to ignore these.

This adds a method to track errors that can be recovered from in
sentry.

It is useful when debugging performance issues, or exceptions that are
hard to reproduce.

This model and the corresponding table will be used for storing settings
specific to CI/CD, starting with the "group_runners_enabled" boolean.

The model is called ProjectCiCdSetting and not ProjectCiCdSettings. The
project exporter doesn't like plural model names as it uses "classify"
which turns those into singular (so "ProjectCiCdSettings" becomes
"ProjectCiCdSetting", producing an error if said class is undefined).

The initial work in this commit was done by Dylan Griffith, with most of
the migration work being done by Yorick Peterse.

This is called repeatedly when viewing a merge request, and this should
improve performance significantly by avoiding shelling out to git every time.

This should help https://gitlab.com/gitlab-com/infrastructure/issues/4027.

Direct disk access is impossible on environments where components run in
their own container. There for constructing the path should not be done
except for exceptional cases.

One of the considerations, instead of logging, was to use Sentry. For
now I've chosen not to use this as the impact of this change is hard to
determine. Getting this in now will allow us to checkout the impact on
dev.gitlab.org and staging.

Part of the Gitaly migration as tracked in: https://gitlab.com/gitlab-org/gitaly/issues/401

Acceptance testing was done in: https://gitlab.com/gitlab-org/gitaly/issues/1014

Fixes gitaly#1126

Clients can now request the attributes from `$GIT_DIR/info/attributes`
through Gitaly. The Gitaly migration is described in gitlab-org/gitaly#1082.

The parser algorithm was implemented in a way it could handle both file
contents or a File handle, and both were already tested.

Other than that, using the boy scout rule, I've removed a class,
InfoAttributes, as it was delegating everything to the parser and
therefor wasn't really needed in my opinion.

It also adds a fallback that covers other edge cases that might surface
later.

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.