Typed Dimensions are a prerequisite to new Dimension Filter operations

[efronbs]

New filter operations on dimensions are currently being implemented. These include comparisons for numeric value dimensions and ranges for dates. To validate that a request using one of these filters is operating on an appropriate dimension, typed dimensions must be introduced.

The solution is to add an interface for dimensions with types and an interface for the types, which includes how to compare them. A default set of types should also be added.