Add iChannelResolution uniform

[Vipitis]

part of #4

iChannelResolution[4] is an array of length 4. Each vec3 has the shape (x, y, aspect). Where pixel-aspect is always 1.0 it seems. reference
Due to the shape, padding is needed. Padding is set to -99. Perhaps there is a better solution for this.

Todos:

• add uniform for glsl
• add uniform for wgsl (also test this)
• improve example/test (also dependencies!)