chore: Consolidate texture implementations, move setters to AsyncTexture (v9.2)

[ibgreen]

For #

Background

• Opening against 9.2-dev branch.
• Continued Texture cleanup, targeting one of the hardest to maintain areas of luma.gl
• Keep Texture minimally focused on exposing GPU capabilities, move convenience methods to AsyncTexture

Change List

• Remove duplicated code between WebGL and WebGPU, simplify texture implementations, move sharable, non-platform-specific functions to AsyncTexture,