Programmatically remove banding with noise

Describe the problem

Banding is present in our texture based iridescence features and gradient features:

Describe the solution you'd like

Would be good to have an option in the GT/Standard and GT/Standard Canvas shaders to remove banding via a technique like this: Removing Banding in Linelight | pixelmager.github.io

Means we can use compressed textures and not worry about banding as much.

Describe alternatives you've considered

Use uncompressed textures or deal with banding.

Additional context

Related to: https://github.com/microsoft/MixedReality-GraphicsTools-Unity/issues/21

Beginne damit, die im Issue genannten GT/Standard- und GT/Standard Canvas-Shader zu finden, und lies anschließend den verlinkten Artikel „Removing Banding in Linelight“. Als abgeschlossen gilt die Arbeit, wenn beide Shader eine Option zur Reduzierung von Banding anbieten, die die texturbasierte Irideszenz und Gradientenmerkmale verbessert und gleichzeitig komprimierte Texturen unterstützt.