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

まず、issue で名前が挙げられている GT/Standard および GT/Standard Canvas シェーダーを見つけ、次にリンク先の Removing Banding in Linelight の記事を読んでください。完了条件は、両方のシェーダーがバンディング低減オプションを提供し、テクスチャベースの虹色効果とグラデーション機能を改善しながら、圧縮テクスチャをサポートすることです。