Replace usage of UIColor.Photon.White100

[lmarceau]

📄 Context

We have deprecated colors in our app under photon-colors.swift we shouldn't be using anymore. I am creating some tasks so we remove them one by one to ensure we make small PRs and evaluate colors usage per their context.

✏ Requirements

1. GradientProgressBar and TopTabFader both uses  UIColor.Photon.White100. Let's replace those with UIColor.white. This will avoid a redesign and remove the deprecated color system.
2. Put screenshots of before/after in your PR in light and dark mode of the affected area. There should be no visual changes.

Note; if UIColor.Photon.White100 isn't used anymore, you can remove it from the photon-colors.swift file

ℹ️ Reference Person

@lmarceau

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