Add tonemapping options to graphics settings

[ksuprynowicz]

Graphics settings should have a part or tab with advanced settings, and that section should feature different tonemapping algorithms, such as Filmic. We already have these algorithms available but they are accessible only from luci.js.

[SilverfishVR]

It should also include exposure setting: Render.getConfig("RenderMainView.ToneMapping")["exposure"]
and AO: Render.setAmbientOcclusionEnabled()

I think the Render API also provides ways to configure AO setting but I can't remember how.

[HifiExperiments]

now that tonemapping is configurable through zones, I don’t think it makes sense to expose this in the graphics settings. you can still override this using luci, but at least for now, I think we can close this