pdl: Define exhaustive array tests

Add test constructs for all possible array types
based on the combination of type (byte, scalar, enum,
static struct, dynamic struct) and size (constant,
with size field, with count field, undefined)

Test: atest --host pdl_python_generator_test
Change-Id: Ide5f90fa18e7be17660f3c45c4d6972662556127