Localized-IBL implementation

[Starkium]

I don’t actively test in Forward so I don’t know at this point but I did try it when I first made the implementation.
everything seemed to work normally with the exception that toggling the feature via cvar would not instantly and would require to recompile all shaders (so setting the cvar in the config file before launching the editor would do it)

All the materials error out for me so I don’t think it works in forward. There are material nodes/functions being used that are not available in forward. I’d really appreciate it if you could look at that and see if you can do anything about this as forward render SORELY needs this project.