ifcopenshell.validate to catch invalid entities used in entities attributes #6409

Example

```
For instance:
    # 1 =IFCCARTESIANPOINT((5.,5.,nan.));
Entity with name 'nan.' not found in schema 'IFC4'
```

src/ifcparse/IfcParse.cpp

@@ -726,7 +726,7 @@ void IfcParse::IfcFile::load(unsigned entity_instance_name, const IfcParse::enti
                     context.push(simple_type_instance);
                     simple_type_instance->file_ = this;
                 } catch (IfcException& e) {
-                    Logger::Message(Logger::LOG_ERROR, e.what());
+                    Logger::Message(Logger::LOG_ERROR, std::string(e.what()) + " at offset " + std::to_string(next.startPos));
                     // #4070 We didn't actually capture an aggregate entry, undo length increment.
                     return_value--;
                 }