Add toggle to Zen themes in Settings so we can deactivate those themes without uninstalling it first.

[KiKaraage]

How it looked right now:

We have to Remove Theme if we don't want to use a theme for a while - Having to go back and forth to Theme Store is not effective, especially during the Vercel era when we encounter lots of failed verification every time we access the site.

Adding toggle to each theme would be much, much better, like this

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Here are some references:

Reference 1: Firefox "Manage extensions" menu

Reference 2: BetterDiscord plugin menu