Add AAsset_seek_impl

[JeodC]

This PR adds AAsset_seek_impl which is a reimplementation of AAsset_seek.

[JeodC]

After thorough testing and rewriting, I have simplified the commits here and ensured backwards compatibility. The AAsset struct now features a persistent_read boolean which inits to false, and is set to true if AAsset_seek is called. In addition, in order to retain compatibility with some ports, I reverted a commit that stubbed all extensions--they now load natively as expected.

The following ports were tested with this build:

• Dokimon
• UFO 50
• Victory Heat Rally
• Dark Deity 2 (known to use AAsset_seek)
• Zelda II Enhanced (armhf)

All boot and play as expected.

[JeodC]

Latest commit moves stubs into a new subfolder, with stubs_gameframe.cpp and stubs_steam.cpp to keep libyoyo.cpp tidy.

[JeodC]

I would like someone else to check over my work here before merging. Dark Deity 2 boots, but is unable to load into a level properly:

texture_is_ready(): Texture group TG_Transitions not found
texture_prefetch(): Texture group TG_Transitions not found
texture_prefetch(): Texture group TG_combatoverlay not found
AAsset_seek_impl: seek offset 651344125719283977 out of bounds (size=2655611)
/storage/roms/ports/Dark Deity 2.sh: line 54: 32738 Segmentation fault      (core dumped) ./gmloadernext.aarch64 -c gmloader.json

I had it working prior a cleanup and backwards compatibility rewrite, so I might be missing something.

[JeodC]

I would like someone else to check over my work here before merging. Dark Deity 2 boots, but is unable to load into a level properly:

texture_is_ready(): Texture group TG_Transitions not found
texture_prefetch(): Texture group TG_Transitions not found
texture_prefetch(): Texture group TG_combatoverlay not found
AAsset_seek_impl: seek offset 651344125719283977 out of bounds (size=2655611)
/storage/roms/ports/Dark Deity 2.sh: line 54: 32738 Segmentation fault      (core dumped) ./gmloadernext.aarch64 -c gmloader.json

I had it working prior a cleanup and backwards compatibility rewrite, so I might be missing something.

Latest commit resolved this and I verified it works with other gms ports as well. In summary, the issue appeared to initially be:

• Gmloader would open an asset and make it persistent
• The game would successfully read the asset, but would then try to seek a different asset
• Gmloader did not change to the new asset, resulting in the out of bounds error (most likely due to having an ogg file open and then trying to seek the much larger data.win)

Now the asset closes when done seeking giving us a clean slate.

[JeodC]

Converting to draft, will rebase off gamechange branch once merged.

[JeodC]

Also cherry picked upstream