Software reflections for forward pass

[HydrogenC]

Add software reflections support for forward pass materials, fixes #2703.
Note: Now SDF reflections is enabled together with SSR, and it takes 7 texture slots and it's costly, so maybe we shall add a separate material option to enable or disable it to avoid waste of texture slots.

Showcase:

The third picture may not look as good as the first one since there's no SSR blurring in forward pass, but it quite resembles the first overall. The strange patterns (also seen in the opaque version) are due to the inaccuracy of the SDF itself, not caused by rendering artifacts.

[abrasivetroop]

my hero 😱😱 can we get this in master asap?

[HydrogenC]

Note: This change would crash the engine due to size mismatch of the buffer if the material shader isn't recompiled after the code change, so it would be necessary to flush the material shader cache and recompile with the new forward template. How to force the engine to rebuild all materials?

[mafiesto4]

Incrementing macro MATERIAL_GRAPH_VERSION handles material shaders regeneration. I'll take care of that during merge.