feat: support iOS 13+ dark mode

[ericlewis]

Description

This PR enables iOS dark mode support. It does not affect any views that clearly were intended to be only dark nor any accent colors that were against non-changing color schemes (i.e. pause menu). Settings and all it's children views as well as the cheats screens have been updated.

Opinions

Alert Boxes & action sheets, however, do pick up on the system color. I personally like this, but we could force them to be brighter as well.

Testing

• I am aware that Initial support for iPad and iOS 13 system colors. #18 exists, but this is a more focused and testable approach to ensuring that we get the colors at least right.
• I have tested every screen that I touched to also ensure it works correctly.
• I have tested against iOS 12.2 (min supported version) with everything looking great.

Screenshots

Light	Dark

[ericlewis]

this could probably serve as a good basis for how difficult it is to switch to an entire custom theming method too.

[rileytestut]

Appreciate the small PR, everything looks good to me 👍 Thanks so much for doing this!

[hmzbg]

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