Add a hex to UIColor converter

Thanks for this awesome tool :)

One of the main features I was missing while using Flashlight was a simple conversion from hex value to UIColor. I'm aware of the fact that you already wrote a similar script but it lacked that simple feature so it might be better to merge these tools or whatever you think works best.

Let me know what you think. I'm not a seasoned python dev so you might check that out too before merging just so you know ;)