This MR adds the ability to add files to comments, notes, replys, and MR descriptions via a picker.
The file will get uploaded to Gitlab and the filepath will be automatically added into the current popup buffer at the current line. You can then save the changes with the normal save functionality.
BREAKING CHANGE: This MR addresses an underlying issue with the original implementation in regards to detecting line numbers for comments.
As such, this is a major breaking change. The setup function signature has changed, please review the `README.md` for the new arguments. The delta pager has also been added as a dependency: https://github.com/dandavison/delta
There will be future work to implement a native solution for parsing changes and line numbers.
