Deprecate setValidator method in builders for ListAttributeDefinition and MapAttributeDefinition

Let's discuss before doing anything on this.

For lists and maps, the builder call to setValidator is really a call to setElementValidator, with a call to set[List|Map]Validator being necessary if some special validation of the overall list/map is desired.

We should deprecate setValidator to help emphasize to people that really setElementValidator is what is happening.