Handle all sType structures in serialisation, and next chain handling

* In many cases these structs are redundant and currently aren't ever serialised
  directly or valid to be included in next chains. However it's better to take
  the hit now and implement this universally in case new structs are needed in
  future. It's easier to keep up with when new structs are added, and it means
  we have the compiler checking we've handled all structs and don't forget one.
* There are some specific exceptions for structs that really need special
  handling and are just treated as if they're unsupported, on the assumption
  that any special handling will be implemented elsewhere.