Fixes #1051

Function changes:

• inheritance + surrogates can now be combined
• emit dll re-enabled on net9+
• new option on compile-options to force "long" jumps

Cleanup needed:

• regression inheritance + surrogate + interface; decide how to respond
• possible protoc drift (tests only)
• CI may need net9
• release notes
• check behaviour of non-root deserialize (where payload is not explicitly the subclass, or example: empty stream)
• do we need type-targeted operator invoke? I think that might be trivial now
• check "helper" type flags are correct for static class (I "fixed" them when investigating the rtspecialname runtime change, probably in error)
• consider back-compat drift; v2 impl kinda does the wrong thing and can double-serialize data - probably combination of inheritance+surrogates not fully considered in v2

Future work:

• protogen for low-effort AOT?