Basis Compression: allow user to prioritize VRAM over quality

[Kulodo]

Currently with Basis the "most desirable gpu texture compression format given the device's capabilities" is defined in the following function.

https://github.com/playcanvas/engine/blob/master/src/resources/basis.js#L268

However, there are cases where a developer needs to choose the format that consumes the least VRAM rather than the format with the best quality.

It would be most flexible if the user could choose "per texture", via the texture inspector basis settings, whether to prioritize VRAM or quality.

Here is the forum thread

https://forum.playcanvas.com/t/basis-compression-ios-android-issue/20317

[Maksims]

I believe this is based on what compressed texture file formats are supported by the end platform and can be transcoded from basis.
PVRTC for example, does support 2-bit and 4-bit per block, few other texture formats do support different block sizes too.

It is worth investigating the list of supported by transcoder formats.