Add typeSymbol() API for applicable constant pool entries

5 Constant Pool entries, namely ConstantDynamicEntry, InvokeDynamicEntry, FieldRefEntry, MethodRefEntry, and InterfaceMethodRefEntry should have a typeSymbol() API to return the nominal/symbolic descriptor (ClassDesc or MethodTypeDesc).

This API is not added to NameAndTypeEntry itself, for a NameAndTypeEntry only knows if its type should be a field or method type from the other entries that refer to it.

This is one of the issues discussed in this mailing list thread: https://mail.openjdk.org/pipermail/classfile-api-dev/2023-June/000381.html