Made StandardMultilayerPBR hide a layer's property groups when that layer is disabled.

ATOM-14688 Disable Individual Layers

- Added new SetMaterialPropertyGroupVisibility functions to the material functors.
- Updated the MaterialFunctor::EditorContext to include parameters for handling material property group metadata.
- Updated the material inspector(s) to apply the property group visiblity changes from the material functor, to hide or show the property groups.
- Moved some code from MaterialPropertyDescriptor.h/cpp to a new MaterialDynamicMetadata.h/cpp, since these aren't really related to the MaterialPropertyDescriptor code. It's more for material functors to use.
- Also fixed the casing for the "GetMaterialPropertyValue_Image" lua function, since I was already in this code (ATOM-14793 "Fix Inconsistent Casing For LuaMaterialFunctorRuntimeContext")

Tested in MaterialEditor and in in the main Editor's MaterialComponent property override inspector.

Gems/Atom/RPI/Code/Source/RPI.Public/Material/MaterialSystem.cpp

@@ -32,6 +32,7 @@ namespace AZ
             MaterialPropertiesLayout::Reflect(context);
             MaterialFunctor::Reflect(context);
             LuaMaterialFunctor::Reflect(context);
+            ReflectMaterialDynamicMetadata(context);
         }
 
         void MaterialSystem::GetAssetHandlers(AssetHandlerPtrList& assetHandlers)