Material: Compatibility with older FCMat files

Provides compatibility loading older files outside the context of
a library.

Older material files were loaded by specifying a path. The new
material system used the path to associated the material with a
library, which may not be appropriate for legacy files. This change
allows the use of materials outside of a library.

Additionally, legacy files often have name/value pairs not part of the
standard list of properties. Since these were unable to be mapped to
a model property they were ignored. Materials now maintain a legacy
map to hold properties not associated with a property model. These
properties are considered transient and will not be saved. It is not
intended for this feature to be used as a generic container for
properties not mapped to an appropriate model.

Fixes #13302

src/Mod/Material/App/MaterialManager.cpp

@@ -196,6 +196,17 @@ std::shared_ptr<Material> MaterialManager::getMaterialByPath(const QString& path
         }
     }
 
+    // Older workbenches may try files outside the context of a library
+    {
+        QMutexLocker locker(&_mutex);
+
+        if (MaterialConfigLoader::isConfigStyle(path)) {
+            auto material = MaterialConfigLoader::getMaterialFromPath(nullptr, path);
+
+            return material;
+        }
+    }
+
     throw MaterialNotFound();
 }