Implement compare revisions kebab menu and "View file @ [SHA]" item

What does this MR do and why?

For #561794 (closed)

Implements the kebab menu with View file @ [SHA] for Rapid Diffs diff files.

References

• A prior implementation of the same menu in a different part of Rapid Diffs: !182222 (merged)

Screenshots or screen recordings

The initial scope of this change was just to add the menu for the Compare Revisions page, so those screenshots are below.

Before	After

Now that the scope has expanded to "all Diff Files shown by Rapid Diffs," there are multiple places this change will show.

For example, below is the main Merge Request diff files display:

Before	After

How to set up and validate locally

1. Have a branch that differs from another branch (like a branch with changes from main)
2. Visit the compare revisions page: /-/compare?from=master&to=master
3. Update the from/to branches to be your correct branches
4. Click "Compare"

MR acceptance checklist

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