Merge branch 'mr-file-path-copy-btn' into 'master'

Added copy file path button to diffs

## What does this MR do?

Adds a copy file path button in the header of diff files.

## Screenshots (if relevant)

![Screen_Shot_2016-10-10_at_09.59.48](/uploads/1aedd5033bb3c1893023bb8c8d99a708/Screen_Shot_2016-10-10_at_09.59.48.png)

## What are the relevant issue numbers?

Closes #23108

See merge request !6769