Improve Lazy Image Loading by using IntersectionObserver

Closes #49511 and #35476

See merge request gitlab-org/gitlab-ce!21565

Update to Rouge 3.3.0 including frozen string literals for improved memory usage

See merge request gitlab-org/gitlab-ce!22035

Add link component to download viewer component

See merge request gitlab-org/gitlab-ce!21987

Add link component to user avatar link component

See merge request gitlab-org/gitlab-ce!21986

Add custom header for error responses

Closes #23197

See merge request gitlab-org/gitlab-ce!21870

Add variables on pipeline webhook

See merge request gitlab-org/gitlab-ce!18171

Improve empty project placeholder for non-members and members without write access

Closes #45589

See merge request gitlab-org/gitlab-ce!21977

[master] Fix syntax highlight taking too long

Closes #2697

See merge request gitlab/gitlabhq!2467

[master] Fix XSS on Issue details page.

See merge request gitlab/gitlabhq!2468

[master] Fix XSS vulnerability sourced from package.json's homepage

Closes #2702

See merge request gitlab/gitlabhq!2496

[master] CE: Project group approvers leaks private group info

See merge request gitlab/gitlabhq!2488

[master] Stored XSS in Gitlab Merge Request from imported repository

See merge request gitlab/gitlabhq!2492

Enable frozen string in lib/api and lib/backup

See merge request gitlab-org/gitlab-ce!22005

[master] - Do not persist errors from Kubernetes calls

See merge request gitlab/gitlabhq!2506

[master] Redact events shown in the events API

See merge request gitlab/gitlabhq!2514

Encrypt webhook tokens and URLs in the database

Closes #51021

See merge request gitlab-org/gitlab-ce!21645

Fixes modal button alignment for protected branches

The buttons in the footer were misaligned due to our CSS
styling only buttons correctly. The CSS was updated to
look for the first element regardless of its type.

Closes #45453

See merge request gitlab-org/gitlab-ce!22024

add a note about reverse proxy to the configuration section

See merge request gitlab-org/gitlab-ce!21951

Set public email through api

Closes #37675

See merge request gitlab-org/gitlab-ce!21938

Update link to documentation testing

See merge request gitlab-org/gitlab-ce!22018

Cleanup review apps more rapidly

See merge request gitlab-org/gitlab-ce!22019

Prevent Error 500s with invalid relative links

Closes #52009

See merge request gitlab-org/gitlab-ce!22001

Resolve "Private profile help url should not toggle checkbox"

Closes #51476

See merge request gitlab-org/gitlab-ce!21757

Every browser which supports IntersectionObserver will now use it over
observing scroll and resize events. Older browsers without support fall
back on the previous behavior.

Additionally the MutationObserver can be enabled and disabled manually
via the helper method `startContentObserver` and `stopContentObserver`.
This might prove useful on pages where we manipulate the DOM
extensively.

Adds list_last_commits_for_tree as the method call for the Gitaly ListLastCommitsForTree RPC

Closes #37433

See merge request gitlab-org/gitlab-ce!21921

Keep IDE RightPane views alive

See merge request gitlab-org/gitlab-ce!21980

Fix link handling for issue cards.

Closes #48445

See merge request gitlab-org/gitlab-ce!21910

Implements list_last_commits_for_tree to communicate with the
ListLastCommitsForTree Gitaly RPC

Bumps the Gitaly server version

Bumps the Gitaly-Proto gem version

- Stop review app's environment after 2 days
- Delete review app's environment after 3 days
- Delete Helm release after 4 days
Signed-off-by: Rémy Coutable <remy@rymai.me>