Adds a universal way to get thumbnail images.
- `thumb:entities/sents/npc/scientist.sent` - resources/assets
- `thumb:mount://ns2/ns2/models/effects/exosuit_part1.model.vmdl` -mount files
- `thumb:facepunch.snowman` - packages
This greatly simplifies UI like the spawnmenu that needs to show thumbnails for these things.
We also add `AssetTypeFlags.IncludeThumbnails`. If this is set then when the package is published, any asset types with this flag will include a "[path].c.png" thumbnail image of it.
Also does Api++ protocol increase.
Games with multiple archives can have multiple files with same names through their archives, either for HDD/CD seek optimization with sequential access redundancy or patch versioning
We don't even support duplicate file names in archive loading but they'd be added regardless to our list & UI
