Feature: Imgui: tonemapper UI

[Trico-Everfire]

Which component should be improved?

Tools

Describe your feature suggestion in more detail

env_tonemap_controller is an entity responsible for a map's general tone in lighting and it's exposure. Console commands like mat_autoexposure_min/max help us get the right values to a map's minimum and maximum auto exposures. There are also more values tonemapper is responsible for: https://developer.valvesoftware.com/wiki/Env_tonemap_controller It would be nice to have a Imgui ui for the tonemapper, allowing us to have an easier time prototyping the map's lighting and the tone of the map. A bunch of cvars for this are already present (like the ones mentioned above) however some like mat_bloomscale are missing, as they are present in other source games.