I ran into a few minor issues with the constructors to the Field class.

The big change I made was that I removed the Field constructors that
take an example type and create an empty field of that type. The problem
was that the example type was easily confused with some other type that
was supposed to describe an array. This lead to some odd behavior in the
compiler and resulted in errors in unexpected places.

The use case for this constructor is dubious. There were several tests
in the code that would create an empty field, add it to a data set, then
get it back out to pass to the worklet. The code is much simpler if you
just make an ArrayHandle of the right type and use that in the worklet
invoke directly. It is also faster to compile with smaller code because
the type is known statically (whereas it is lost the other way).

The other change was to declare references to ArrayHandle and
DynamicArrayHandle as const. There is nothing in the behavior that
invalidates the const, and it accepts arrays constructed in the
parameter.