Updated dithered transparency to support blue noise

[mvaligursky]

Update to transparency dithering introduced here: #5903, which is not released yet and so API changes are fine.

New API (booleans were changed to enums to allow different options)

StandardMaterial.opacityDither = DITHER_BAYER8 / DITHER_BLUENOISE / DITHER_NONE;
StandardMaterial.opacityShadowDither = DITHER_BAYER8 / DITHER_BLUENOISE / DITHER_NONE;

• added internal data storing 32x32 4 channel blue noise, which will be used for multiple effects together with TAA
• the data gets also uploaded as a texture (initially used for blue noise dithering only)
• when the camera jitter is enabled (TAA), both bayer and blue noise pattern are randomly per frame offset by a blue noise based offset

Existing bayer dithering:

Blue noise based (better with TAA):

Related: #5943