UIColor sheet has color sets per theme. Updated `UIColorWidget` to
reflect that, and added `SeStringDrawParams.ThemeIndex` to let users
choose which theme color set to use while drawing SeString from Dalamud.
* Add coloring options
* Add link support
* simplify
* fixes
* Prevent EncodeString from causing crashes
* Fix link range application and add link example
* Fix test widget
* Make DalamudLinkPayload backward compatible
* make it better to use
* make it better to use
* Mark SeString rendering functions experimental via comments
* rename
* Simplify
* Make sestring draw functions take in draw params
* Improvements