Consider array params on rendering MR list on dashboard

See merge request gitlab-org/gitlab-ce!26623

(cherry picked from commit 7926384f)

b3f5413a Consider array params on rendering MR list on dashboard

Previously, you could only access personal snippets in the API if you
had authored them. The documentation doesn't state that this is the
case, and it's quite surprising.

Since the CTE is faster than a subquery and the only reason we're using
a subquery is that the CTE can't handle sorting by certain attributes,
let's use the CTE always (when the feature flag is enabled) when
counting, since we can ignore ordering if we just want a count of
results.

Due to performance reasons we cannot use the type filter on the tags.
The table for ActsAsTaggableOn is too big and too unoptimized, such that
the queries time out on production.

See the discussion
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/19740#note_120087938
for more info.

The query generated by ActsAsTaggableOn `@taggable_type.all_tags` is
very inefficient (joins too much, grouping, inner select, ...).

the potential number of available runner tags is too large to load it
statically to a dropdown. we use the same lazy loaded dropdown as is
used for the users dropdown already.

The API get projects/:id/traffic/fetches allows user with write
access to the repository to get the number of clones for the
last 30 days.

As discussed in https://github.com/mbleigh/acts-as-taggable-on/issues/91,
we can avoid N+1 queries if we use `tags` instead of `tag_list`.

Seen while reviewing
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/19740.

Fix misspellings in app/spec comments

See merge request gitlab-org/gitlab-ce!25517

Ability to filter confidential issues

Closes #50747

See merge request gitlab-org/gitlab-ce!24960

This reverts commit 9202bbd1, reversing
changes made to 4b282e9c.

This reverts commit d133bf84, reversing
changes made to 7981c029.

Signed-off-by: Takuya Noguchi <takninnovationresearch@gmail.com>

Use internally only boolean params.

Add a new search bar filter for confidential issues. Add filtering
support to the IssuesFinder.

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

We shouldn't care about the ordering here; if we did, it would be more
appropriate to use `take` or `first`. Having the ordering can result in
the database picking a bad query plan, as it might think sorting the
whole table first is the best option.

Adds to search ILIKE search for milestones title in:
  - Milestones dashboard
  - Group milestones page
  - Project milestones page

Instead of querying relations into ids we just pass them to the model
scope because the scope supports it now.

Also changes other calls to `Milestone.for_projects_and_groups`

Refactored to use Rails 5 ActiveRecord `or` so that it can handle ids,
objects, array of objects, or relations properly.

This commit introduces Releases API under /api/v4/projects/:id/releases

* We are introducing release policies at project level.
* We are deprecating releases changes from tags, both api and web
interface.
* Tags::CreateService no longer create a release

This feature is controlled by :releases_page feature flag

- we now use the hierarchy class also for epics
- also rename supports_nested_groups? into supports_nested_objects?
  - move it to a concern

We're filtering the events using `Event#visible_to_user?`.

At most we're loading 100 events at once.

Pagination is also dealt with in the finder, but the resulting array
is wrapped in a `Kaminari.paginate_array` so the API's pagination
helpers keep working. We're passing the total count into that
paginatable array, which would include confidential events. But we're
not disclosing anything.

Given the note is about how to interpret ancestor clusters, use the
finder which actually knows if there are any ancestor clusters to find
out if the note should be shown, rather than passing the same info via a
view to a helper

Added note about Kaminari.paginate_array

Link to followup issue too

This is in addtion to the can checks we have in the controller, as a
finder can be used elsewhere in the future.

Show both the cluster(s) of the clusterable, and the cluster(s) of
ancestor groups.

The email is sent to project maintainers containing the last mirror
update error. This will allow maintainers to set alarms and react
accordingly.