[4.2][Feature request] Dark Mode

[tabacitu]

Since MacOS & iOS have dark mode too now, it could make sense to create a new overlay for dark mode, and have a use toggle between Auto, Light and Dark.

https://nandovieira.com/supporting-dark-mode-in-web-content

Of course, dark mode websites look pretty bad right now - design-wise they’re still a long way from light designs.

But we could do this... Food for thought. And feedback.

[martijnb92]

Great idea!
It would be really nice to have a dark mode in Backpack.
Some things to think about before working on a dark mode overlay:

• Will Backstrap be upgraded to CoreUI 3?
• Will this cause issues with CoreUI since they have a dark layout included in the Pro version?
• How to deal with the different color schemes currently available?