This enables FindCommit caching to the following actions:

* BlobController#show
* RefsController#logs_tree

It also improves caching in CommitsController since some
duplicate requests were occuring inside the before_action
definitions.

This reduces a handful of duplicate FindCommit calls while viewing the
projects and commits pages.

Before a 404 would be rendered only after a request to Gitaly would
return with an InvalidArgument error. Now we check that the ref have a
valid format before sending it to Gitaly. In both cases, a 404 is
returned to the user, but this change prevents Gitaly from generating
error noise in production.

Closes https://gitlab.com/gitlab-org/gitaly/issues/1425

This reverts commit 6da19415.

# Conflicts:
#	app/controllers/projects/commits_controller.rb

[master] Resolve "Personal access token with only `read_user` scope can be used to authenticate any web request"

See merge request gitlab/gitlabhq!2583

Enables frozen string for some vestigial files as
well as the following:

* app/controllers/projects/**/*.rb
* app/controllers/sherlock/**/*.rb
* app/controllers/snippets/**/*.rb
* app/controllers/users/**/*.rb

Partially addresses #47424.

This whitelists all existing offenses for the various CodeReuse cops, of
which most are triggered by the CodeReuse/ActiveRecord cop.

When a diff has a significant number of commits, the previous behavior would
attempt to render the Markdown on all the commit messages but only display
1000 of them. To avoid additional work, we only need to render the Markdown
on the set that is displayed.

Since Rails 5.0 `request.format` is being set depending on the route extension.

In commits pages we pass a ref as a URL parameter.
If the ref is an extension-like, Rails converts it and sets to
`request.format`.

E.g. if the ref is `some_branch.atom`, Rails starts responding with
`atom` format, but it should response with `html` because `.atom` is the
part of ref name, not the format.

This commit explicitly sets `request.format` to `:html` when needed.

Closes gitaly#1046

This ensures that we have more visibility in the number of SQL queries
that are executed in web requests. The current threshold is hardcoded to
100 as we will rarely (maybe once or twice) change it.

In production and development we use Sentry if enabled, in the test
environment we raise an error. This feature is also only enabled in
production/staging when running on GitLab.com as it's not very useful to
other users.

This adds an optimised way of getting the latest pipeline status for a
list of Commit objects (or just a single one).

Use Commit#notes and Note.for_commit_id when possible to make sure we use all the indexes available to us

This reverts commit cb10b725c8929b8b4460f89c9d96c773af39ba6b.

Replace MR access checks with use of MergeRequestsFinder

Split from !2024 to partially solve https://gitlab.com/gitlab-org/gitlab-ce/issues/23867

 - Potentially untested
 - No test coverage
 - Test coverage of some sort exists (a test failed when error raised)
 - Test coverage of return value (a test failed when nil used)
 - Permissions check tested

- [x]   app/finders/notes_finder.rb:17
- [x]   app/views/layouts/nav/_project.html.haml:80 [`.count`]
- [x]   app/controllers/concerns/creates_commit.rb:84
- [x]   app/controllers/projects/commits_controller.rb:24
- [x]   app/controllers/projects/compare_controller.rb:56
- [x]   app/controllers/projects/discussions_controller.rb:29
- [x]   app/controllers/projects/todos_controller.rb:27
- [x]   app/models/commit.rb:268
- [x]  lib/gitlab/search_results.rb:71

- [x] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#d1c10892daedb4d4dd3d4b12b6d071091eea83df_267_266 Memoize ` merged_merge_request(current_user)`
- [x] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#d1c10892daedb4d4dd3d4b12b6d071091eea83df_248_247 Expected side effect for `merged_merge_request!`, consider `skip_authorization: true`.
- [x] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#d1c10892daedb4d4dd3d4b12b6d071091eea83df_269_269 Scary use  of unchecked `merged_merge_request?`

See merge request !2033

Closes #23615

- Parameter validation as ISO8601 format

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Jeroen van Baarsen <jeroenvanbaarsen@gmail.com>