[Feature] Add ImGui Support

[Mi1ax]

So, are there any plans to add out-of-the-box ImGui support?
I’ve already made a few tweaks to integrate ImGui into Bliss. It was pretty straightforward since Bliss uses Veldrid as the rendering backend.

My question is: would you be interested in a pull request that adds ImGui support to Sparkle/Bliss?

[MrScautHD]

Hey!
Yes, that sounds fantastic!