[FEATURE] Invalid Mod File Detection

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Is your feature request related to a problem? Please describe.

There are many times when zip files land in the directory that aren't actually mods when downloading from 3rd party sites.

Examples are:
- Zip files that contain the mod zips
- RAR files (these usually contain the mod zips also, and are done as RAR so game doesn't pick them up and error)
- Zip files that are just invalid, ie. no modDesc.xml file in them

### Describe the solution you'd like

Check for valid mods, and suggest remedies for invalid ones.

Such as:
For RAR and ZIp that contain actual mod Zip files, report them and suggest unzipping then deleting them.
For Zip files that don't contain other Zip files, and aren't valid mods, suggest removing them completely.

### Anything else?

_No response_

L’issue non indica file, test o punti di ingresso. Inizia individuando il flusso esistente di importazione o scansione dei mod, quindi determina come vengono attualmente gestiti gli archivi e modDesc.xml; il lavoro è completato quando gli archivi non validi sono identificati e vengono presentati i rimedi richiesti senza influire sui mod validi.

Scritto dal modello di indicizzazione a partire dal testo della issue.