- Adds the Int8. Int16, Int64 and GenericPointer capabilities.
  TODO: This should integrate with the feature system.
- Default some struct fields of SPIR-V types so that we dont
  need to type them all the time.
- Store struct field name's in SPIR-V types, and generate the
  OpMemberName decoration if they are non-null.
- Also add the field names to the actual SPIR-V types.
- Generate OpName for functions.