Provide a way to manage items referenced by the project

Basic function offered by the 'collect files' window would be:
For each file referenced by the project:
1/ Displays last known path,
2/ Allows to manually (over)write file path,
3/ Sugests a new location (normalized subfolder, updated path, original path, ...)
4/ Indicate whether file exists or not : No, HQ, LQ,
5/ Checkbox for 'copy' / 'transcode' file from last known path to new path (active only if file exist in last path but not in new path)