[flang] Simplify representation of intrinsic types

Intrinsic types are now just a TypeCategory and a int kind. If no kind
is specified the default is used so that every type has an explicit
kind. This caused changes in the expected results of some of the tests.

Add support for "double precision" and "double complex".

Intrinsic types are now stored as values in DeclTypeSpec so none of the
KindedTypeHelper machinery is needed any more.

Eliminate DerivedTypeDef, DataComponentDef, ProcComponentDef,
TypeBoundProc. The components and bindings of a derived type are now
represented by the corresponding Scope.

Original-commit: flang-compiler/f18@4ad8ffb18708e073da9a0f37c3bb09a271ca1c02
Reviewed-on: https://github.com/flang-compiler/f18/pull/182
Tree-same-pre-rewrite: false