Files that are removed via Filebrowser (or another method such as IMCE) leave behind metadata DB values

Problem/Motivation

Firstly thanks for this helpful module!

I've noticed that when files are deleted, either via the Filebrowser UI or via another method such as IMCE, the content db table gets cleaned up, but the metadata entities remain. Might be better to clean these up as well

Steps to reproduce

1. Have a directory listing node
2. Delete some files
3. Notice the metadata entity values remain in the DB

Proposed resolution

Clean up the metadata entities during removal

Remaining tasks

Clean up the metadata entities during removal