Add RmlSolLua for RmlUi

[zeroxer]

Is your feature request related to a problem? Please describe.

• The default lua binding of RmlUi lacks of some interfaces, but RmlSolLua add them.
• I tried to add https://github.com/LoneBoco/RmlSolLua with package.tools.cmake but failed on compiling. It seems the deps relation is complex.

Describe the solution you'd like

• Add RmlSolLua to xmake

Describe alternatives you've considered

No response

Additional context

• Does anyone have tried RmlSolLua? @xq114 @zziger

[zziger]

Never used it, but will give a try compiling it a bit later