[CE for Part 3] Update IDE file mirror service (ce utils)

See merge request gitlab-org/gitlab-ce!29360

Backport of EE Displaying Blocking MRs

See merge request gitlab-org/gitlab-ce!29095

**Notes:**
This module is a client to the webide-file-sync service.
https://gitlab.com/gitlab-org/webide-file-sync

Some classes in vue_shared were used only by boards, so they were
moved to the boards directory.

CE backport for Storage Counter changes

Closes #59232

See merge request gitlab-org/gitlab-ce!29206

Use update term instead of update in the clusters managed app
implementation in order to make the implementation and UI
language more consistent.

With this commit, we add docs link for confidential
and locked issues to note compose and edit forms

This copy button manages a local instance of the Clipboard plugin
specific to it, which means it is created/destroyed on the
creation/destruction of the component. This allows it to work well in
gitlab-ui modals, as the event listeners are bound on creation of the
button.

It also allows for bindings to the `container` option of the Clipboard
plugin, which allows it to work within the focus trap set by bootstrap's
modals.