Preference to change orientation of NumberBond and BarModel in Sum screen.

[marlitas]

I want to…
Provide the option to change the sum number bond to match the first three screen’s orientation rather than forcing the bond to be “upside down.”

This is pedagogically important because…
Some curriculum this screen would be embedded in might not match the sim

[pixelzoom]

Discussed with @marlitas to clarify:

• This supports a user story in the PhET-iO design doc.
• This applies to "Number Bond" and "Bar Model" representations.
• This should be a Preference, and we'll have 2 radio buttons that show a picture of the 2 choices based on the selection for "Number Model Type" preference. Use kitten colors.
• There is a totalOnTop attribute that we can investigate coverting to sumScreenTotalOnTopProperty for the Sum screen.
• We should have sumScreenTotalOnTop query parameter.