Add support for Write Groups

[psuong]

Write groups allow other devs to override the current systems. The purpose of UGUIDots is similar to DearImGUI which is to provide vertex and index buffers for you to render. So if you want to override the current rendering system - then it's feasible to do without having to create virtual class overrides.

Supposedly the current transform system for entities uses write groups to override certain systems on certain conditions - which is a good place to start looking at.