Update etcpak to 2.0

[BlueCube3310]

Depends on #89567

Updates etcpak to 2.0, the latest official version. Said version also includes bc7enc as a dependency (though not used by Godot's importer), should it be removed with a Godot-specific patch?

[fire]

It makes sense to add a readme addition to remove bc7enc

[clayjohn]

It looks like all this does is remove CompressEtc1Alpha and CompressEtc2Alpha and adds CompressBc7. But I guess it would be nice to be back on an official release.

Is there any value in us using the BC7 compression here? Or do we use a different/better library already?

[BlueCube3310]

The BC7 compression is much faster than CVTT (what Godot uses currently), although the quality is generally lower (only 4 block modes are available) and most of the performance improvements require SSE4/AVX2.

[clayjohn]

The BC7 compression is much faster than CVTT (what Godot uses currently), although the quality is generally lower (only 4 block modes are available) and most of the performance improvements require SSE4/AVX2.

Ah, so probably not worth integrating yet. I would do a Godot-specific patch to remove it just due to the size

[BlueCube3310]

I'm closing this for now as the upstream changes aren't significant to Godot's implementation, plus now it requires a patch.