UI: Install textures as a zip if supported

[unknownbrackets]

This makes the zip installer copy a textures.zip file into place without extracting it.

To use:

• Make sure the textures.zip file contains the textures.ini file on the root (not inside a folder.)
• Make sure all the PNG or ZIM files are also inside the zip. It should contain the entire texture pack.
• Make sure the textures.ini contains [games] and has an entry such as ULUS12345 = textures.ini for your game (you can also use region-specific ini files if you wish, but using = textures.ini makes them all use the same ini.)
• Simply browse to the zip file within PPSSPP, and try to open it as a game.
• Note: if your texture pack supports multiple games, it will install for whatever game is in the recently played history or else the first game listed.

Also fixes #16313.

-[Unknown]

[hrydgard]

Nice and straightforward!

[hrydgard]

According to #16319 (comment) , this broke some of the separate libretro builds, see link. Struggling to see why though.

[unknownbrackets]

I don't think it can be this one, it would have to be #16304. Might be libretro wasn't linking libzip previously.

-[Unknown]

[hrydgard]

Yeah, seems like it, I don't see the motivation for that check...