DDSXTY13 — Representation of Built-in Annotations in Dynamic Types

A dynamic type cannot be marked as final, mutable or nested and a dynamic type member cannot be marked as key, optional, shared or must_understand easily with the current specification. Only MemberDescriptor has a boolean field "union_default" to represent whether the union member is the default one. Annotations can be used of in the dynamic API but the usage is a bit cumbersome. Is it considerable to append TypeFlag and MemberFlag fields to TypeDescriptor and MemberDescriptor in order to represent built-in annotations in dynamic types as in TypeObject?

TypeDescriptor and MemberDescriptor with information about the built-in annotations.

As indicated in the issue description, the MemberDescriptor and TypeDescriptor types need additional members that provide the value of the builtin annotations.

Define an enum for TypeKind. This was referenced in TypeDescriptor and MemberDescriptor but never defined.
Define an enum for ExtensibilityKind
Define an enum for TryConstructKind
Define VerbatimTextDecriptor

Add the following fields to MemberDescriptor: is_key, is_optional, is_must_understand, is_shared, try_construct_kind

Add the following fields to TypeDescriptor: is_nested, extensibility_kind