Move gates of undetermined types to standard ones where possible

[sanjayankur31]

No description provided.

[sanjayankur31]

TODO:

• add tests
• confirm if we want to keep the second commit (which will update all models as they are read) or if we want to drop it and let this be something the user has to do explicitly (but in which case, they may not be aware of the caveats mentioned in Python object model does not load gates into correct attributes when type= is used #205)