Support CURD operation for feature flag scopes (GitLab API)

See merge request gitlab-org/gitlab-ee!9182

[Part 4] Add support for labels in Epic sidebar

See merge request gitlab-org/gitlab-ee!9315

Prevent unload when Recaptcha is open

Closes #44698

See merge request gitlab-org/gitlab-ce!24625

Update dependency @gitlab/ui to ^1.22.0

See merge request gitlab-org/gitlab-ce!24721

Wait for requests in specs before interacting with select2

Closes #56867

See merge request gitlab-org/gitlab-ce!24694

Adds labels picker within Sidebar.
Supports auto-expanding collapsed sidebar and reveal labels dropdown.

 (GitLab internal API standpoint)

Squashed commit of the following:

commit 32a24ca826bc62d8667980108c1593e8b4377f95
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Mon Jan 21 19:39:01 2019 +0900

    Added another tests

commit 2253909e5c8a3a372f15c21e9a1efac6c5e1d186
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Mon Jan 21 18:16:09 2019 +0900

    Fix unleash spec

commit 1c61c13cf87a6543d22906cb717e46a6daaee212
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Mon Jan 21 18:11:16 2019 +0900

    Add spec for finder

commit c670bf9e3bccaf1422d5718be93ca37cc3afc0ce
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Mon Jan 21 17:55:22 2019 +0900

    Fix model related spec

commit c9913a3d4ab0722b7a8f1bf2fe2b77ffd70a1bf3
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Mon Jan 21 17:22:36 2019 +0900

    Rename lazy active to at least one

commit 6b50d76cd1f5b47162fb94f25c2ebd7f837fd2dd
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Mon Jan 21 16:00:51 2019 +0900

    Fix default scope related code

commit e0c352c0453bbdec6c7e1882663f1f5f99a9a2b1
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Mon Jan 21 14:44:50 2019 +0900

    Fix

commit 3528b8c79c3fb07e0b8327c9195465c555ae7364
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Mon Jan 21 14:44:21 2019 +0900

    Revert "Decouple default scope related things"

    This reverts commit ccbfaf81197c6ab2ac7ad86629701a65807dd996.

commit d396059841c019c53796cf254f6410d81e255407
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Wed Jan 16 19:56:24 2019 +0900

    Support CURD operation for flag scopes

    Simplify active presentation

    introduce lazy sql

    Fix

    Fix finder

    Fix spec

    Improve

commit 52364fa2f2e122eaf4e0abacf1db378244f1f303
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Mon Jan 21 16:07:53 2019 +0900

    Add helper for feature flag tests

commit c781381a5a1dfe65905ab1f94b7b21a2796e8f4e
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Mon Jan 21 15:24:19 2019 +0900

    Fix unleash api app name handling

commit d7e6c0f21bbb90c4f37ecd98e9ddd2a940fcc074
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Mon Jan 21 15:18:21 2019 +0900

    Decouple FeatureFlagsFinder change

commit 032cdb41ed3cc9f28891d16b2ff0eea65e9b6fae
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Mon Jan 21 14:23:22 2019 +0900

    Decouple default scope related things

commit fe3e415d83bd260ae8a4db37323f1909174e2d06
Author: Shinya Maeda <shinya@gitlab.com>
Date:   Thu Jan 10 20:20:45 2019 +0900

    Multiple environments support for feature flags

    Support for Unleash API

    Elaborate a comment in has environment scope

    Fix specs

    Complete test for unleash API

    Add changelog

    Fix coding offence

    Fix coding offence

    Fix ee specific line check

    Fix MySQL problem

    Fix typo

    Improve comment

    Fix spec location

    Override active value with alias

    Add test and feature flag

    Add frozen string literal

    Default enable true

Prevent destroy default scope (A bit messy now)

Simplify the all implementations

Simplify implementaion ver 2

Simplify implementation ver 4

Simplify implementation ver 5

Fix feature flag options

Add changelog

Fix coding offence

Fix spec

Push feature flag to frontend

Update spec

Simplify the implementation more

Fix N+1 problem

Fix coding offence

Bump Sidekiq to 5.2.5

See merge request gitlab-org/gitlab-ce!24662

Feature switch layer around Approvable and VisibleApprovable

See merge request gitlab-org/gitlab-ee!9147

Adds new and edit modules FF store

See merge request gitlab-org/gitlab-ee!9292

Fix `star` action in the `explore` subpages

See merge request gitlab-org/gitlab-ce!24693

[Part 3] Add support for start and due dates in Epic sidebar

See merge request gitlab-org/gitlab-ee!9304

To eager load rules, reuse the association without scope.
Filter those rules using `regular?` method.

as it is no longer needed.

Apply project scope

It is now wished for the feature to be disabled by default.
Since we can't control when the background migration finishes,
which would set the old flag to true,
changing the flag is easier to work around with.

From dev.gitlab repo

DRY maintainer

The logics are copied over but unchanged.

Similar to MergeRequestPresenter

Logic unchanged

Only call ApprovalState when enabled

Add query method for id

See merge request gitlab-org/gitlab-ce!24386

Standardize token value capitalization in filter bar

Closes #54213

See merge request gitlab-org/gitlab-ce!23846

Adds start and due date pickers within sidebar.
Supports for expand and collapsed sidebar states.

Fix create_edit_delete_epic_spec.rb test flakiness

Closes gitlab-org/quality/nightly#63

See merge request gitlab-org/gitlab-ee!9300