New issue shortcut doesnt work on some pages

What does this MR do?

1. Slightly tidies dispatcher switch case by utilising 'fall through' cases.
2. Adds shortcuts to project pipelines, milestones, builds and forks pages

Are there points in the code the reviewer needs to double check?

I have a feeling that these may have been missed out of the case statements on purpose?

Why was this MR needed?

Possible UX issue highlighted in #17929 (closed).

What are the relevant issue numbers?

Closes #17929 (closed).

Closes #12616 (closed). (dup)

Closes #18123 (closed). (dup)

Closes #13688 (closed). (dup)

Screenshots (if relevant)

/cc @jschatz1

mentioned in issue #2117 (closed)

Milestone removed

Removed ~19492 label

Reassigned to @jschatz1

Added 75 commits:

• 57f31318...0f96a6c2 - 74 commits from branch gitlab-org:master
• 574a20e3 - Tidied dispatcher switch and added shortcuts to project pipelines, milestones and forks pages

Added 28 commits:

• 574a20e3...f828b744 - 27 commits from branch gitlab-org:master
• 7a2e5e0f - Tidied dispatcher switch and added shortcuts to project pipelines, milestones and forks pages

Added 1 commit:

• 9cab5708 - Tidied dispatcher switch and added shortcuts to project pipelines, milestones and forks pages

Added 18 commits:

• 9cab5708...e6389dfe - 17 commits from branch gitlab-org:master
• ec32d79d - Tidied dispatcher switch and added shortcuts to project pipelines, milestones and forks pages

Looks good @lbennett! ✨

You have conflicts and I can't fix cause it ain't a GitLab branch.

Also I can't believe we have nested switch statements. That would never occur to me to create those. Assign back to me once resolved.

Reassigned to @lbennett

@jschatz1 Indeed, I would love to take on the shortcuts refactor when it's scheduled. Good opportunity to have fun with tidy patterns!

Added 392 commits:

• ec32d79d...fd248392 - 391 commits from branch gitlab-org:master
• 0798b15b - Tidied dispatcher switch and added shortcuts to project pipelines, milestones and forks pages

Reassigned to @jschatz1

Reassigned to @lbennett

Reassigned to @jschatz1

@iamphill will you review?

Reassigned to @iamphill

@lbennett conflicts 😜

@jschatz1 seems good to me!

Added 261 commits:

• 0798b15b...bedb7114 - 260 commits from branch gitlab-org:master
• 479ecbab - Tidied dispatcher switch and added shortcuts to project pipelines, milestones and forks pages

@iamphill @jschatz1 Rebased :))

Reassigned to @jschatz1

Milestone changed to %8.9

Added ~149423 label

Status changed to merged

mentioned in commit 995a5931

Removed ~149423 label

Picked into 8-9-stable, will be in RC5.

mentioned in commit 063535be