Add feature to check for file link rot

[flightmansam]

I love this plugin and have been experimenting linking some of my project files (.odt/.docx) with some of my notes and todos. Obviously if the filesystem changes then the link no longer works. This tool could have a simple command to check if the and URIs in any notes (following the file:// convention) are broken and create an md listing them? A bit like in https://github.com/Vinzent03/find-unlinked-files (I checked if this one works and it doesn't, alternatively maybe this issue should live in that repo 🤷‍♂️).