Add UI_FEED_* structs and natives to mono_rt2

[AvarianKnight]

Goal of this PR

Implement the structs and natives for UIFEED*, this still needs testing for certain natives as I was not able to get certain UiFeed natives to work, theres also some weird VarString usages that need to be tested and have constructors implemented for

This PR applies to the following area(s)

ScRT: C#, RedM

Successfully tested on

Game builds: 1491

Platforms: Windows

Checklist

• [ ] Code compiles and has been tested successfully.
• [x] Code explains itself well and/or is documented.
• [x] My commit message explains what the changes do and what they are for.
• [x] No extra compilation warnings are added by these changes.

[AvarianKnight]

Closing as i do not plan on finishing this PR, if anyone wants to continue it feel free, its mostly done just likely needs a rebase onto initial implementation my other RedM PR