dear-imgui

As suggested by @connorjak in pyimgui/pyimgui#243 (comment), we should add tests for each integration that would launch the integration and exercise it (call functions and action callbacks).

Notes:

• Tests of actual functionalities are automatically parsed from the examples in the documentation. No need to run every single example for every integration.

I'm working on porting an app from the (frankly shoddy) Kotlin ImGui port, and while overall the change has been a positive one (if painful), I've run into a couple issues with binding support.

The first thing I noticed not being bound was the JImGui.listBox function, along with the itemSize and `itemA