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)

See merge request !4496