Get Rid of Redux for User Preferences/Data

[Arthi-chaud]

The wheel was reinvented. Let's take advantage of popular libraries that do the job for us:

• Use MUI's CSS Variables and useColorScheme hook to access the current theme (light/dark) (Closed with Front: Use CSS Variables #609)
• Use next-i18next to handle translations and language preferences (Closed with Front: i18n without redux #611)
• Use Local Storage Hook for Notification Preferences (Closed with Front: Remove settings redux + Fix Artist Image Fit #617)

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• Regarding the UserSlice, we could get rid of it, and write a custom hook that relies on react-query