theme: Add Tokyo Night variants

[foster-hangdaan]

This PR adds three variants of the Tokyo Night theme:

• Light (Source)
• Storm (Source)
• Moon (Source)

Closes: #827

Screenshots

Tokyo Night Light

Tokyo Night Storm

Tokyo Night Moon

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• [x] I searched the issue tracker and this hasn't been PRed before.
• [x] My changes are not on the do-not-PR list for this project.
• [x] My commits conform to the git conventions.
• [x] My changes are visual; I've included before and after screenshots.
• [ ] I am blindly checking these off.
• [x] Any relevant issues or PRs have been linked to.
• [ ] This a draft PR; I need more time to finish it.