Datatypes with nested recursion are not handled in TheoryDatatypes unless option...

Datatypes with nested recursion are not handled in TheoryDatatypes unless option is set (#3707)

Towards experimental support for non-simply recursive datatypes (https://github.com/ajreynol/CVC4/tree/dtNonSimpleRec). Builds a check for non-simple recursion in the DType class. If a term of a datatype type is registered to TheoryDatatypes for a datatype that has nested recursion, we throw a LogicException unless the option dtNestedRec is set to true. Also includes a bug discovered in the TypeMatcher utility and another in expr::getComponentTypes.

It also adds a unit test using the new API for a simple parametric datatype example as well, not related to nested recursion, as this was previously missing.