Updates clipboard button component to use
the new glTooltipDirective and the new glButton
component from gitlab-ui

Re-implemented image commenting on diffs

Closes #48956

See merge request gitlab-org/gitlab-ce!22443

Instead of rendering all report items in 4 big lists, we make use of
vue-virtual-scroll-list and render only few dozens at once. This
improves the performance in several metrics:

- Initial load time
- Memory Pressure
- CPU Load
- DOM node count

In an example with around 11k reported security vulnerabilities:

- Initial load time: 27s -> 4.1s
- Memory Pressure: ~750 MB -> ~270 MB
- CPU Load (time spent on executing JS/Rendering): 22s -> 2.5s
- DOM node count: 430k -> 7k up to 30k while scrolling

This re-implements image commenting in merge request diffs.
This feature was previously lost when the merge request
page was refactored into Vue.

With this, we create an overlay component. The overlay
component handles displaying the comment badges
and the comment form badge.
Badges are displayed based on the position attribute
sent with the discussion.

Comment forms for diff files are controlled through
a different state property. This is so we don't
tie comment forms to diff files directly creating
deep nested state. Instead we create a flat array
which holds the file hash & the X & Y position of
the comment form.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/48956

Fix typos in comments and specs

See merge request gitlab-org/gitlab-ce!22683