Convert to new approach for Region and Culture

[Luisav1]

For phetsims/joist#958.

The changes were done in 970fe8b.

@amanda-phet This needs a design review to ensure the Region and Culture changes were alright. The changes can be seen in main.

[amanda-phet]

The preferences dialog looks how I would expect. Query parameter is working.

Can we make random the default selection for Region & Culture?

[Luisav1]

Although the default in general for R&C is usa (from phetsims/joist#957 (comment)), @amanda-phet confirmed with @kathy-phet that we'll use random as the default when the usa set is only one character, such as this sim.

Oops, I missed #214 that is tracking changing the default to random.

[Luisav1]

Closing since this has been reviewed and #214 set the default to random.