Add shortcut to copy file content hash link
## What does this MR do?
* Allows for multiple shortcut handlers to be initialised
* Adds `y` shortcut to file pages to copy permalink URL.
## Are there points in the code the reviewer needs to double check?
Ney.
## Why was this MR needed?
UX
## What are the relevant issue numbers?
Closes #14470.
## Screenshots (if relevant)
![y-shortcut](/uploads/b81feb26d8e0d7d4996c4afa29f385d7/y-shortcut.gif)
See merge request !4496