Updated MaterialPropertyId class in preparation for nested material property sets.

Here the class has been generalized for a list of group names and a final property name, rather than assuming a single group containing the property. This included removing the unused GetPropertyName and GetGroupName functions. All that's really need from this class is conversion to a full property ID string.

Testing:
New unit test.
Reprocessed all core material types and StandardPBR test materials used in Atom Sample Viewer's material screenshot test.
Atom Sample Viewer material screenshot test script.

Signed-off-by: santorac <55155825+santorac@users.noreply.github.com>

Gems/AtomLyIntegration/CommonFeatures/Code/Source/Material/EditorMaterialComponentUtil.cpp

@@ -140,7 +140,7 @@ namespace AZ
                 editData.m_materialTypeSourceData.EnumerateProperties([&](const AZStd::string& groupName, const AZStd::string& propertyName, const auto& propertyDefinition) {
                     const AZ::RPI::MaterialPropertyId propertyId(groupName, propertyName);
                     const AZ::RPI::MaterialPropertyIndex propertyIndex =
-                        editData.m_materialAsset->GetMaterialPropertiesLayout()->FindPropertyIndex(propertyId.GetFullName());
+                        editData.m_materialAsset->GetMaterialPropertiesLayout()->FindPropertyIndex(propertyId);
 
                     AZ::RPI::MaterialPropertyValue propertyValue = editData.m_materialAsset->GetPropertyValues()[propertyIndex.GetIndex()];
 
@@ -151,7 +151,7 @@ namespace AZ
                     }
 
                     // Check for and apply any property overrides before saving property values
-                    auto propertyOverrideItr = editData.m_materialPropertyOverrideMap.find(propertyId.GetFullName());
+                    auto propertyOverrideItr = editData.m_materialPropertyOverrideMap.find(propertyId);
                     if(propertyOverrideItr != editData.m_materialPropertyOverrideMap.end())
                     {
                         propertyValue = AZ::RPI::MaterialPropertyValue::FromAny(propertyOverrideItr->second);