Merge to upstream check list

[cpetig]

• string
• list 🚧: Broken by recent pointer vs int distinction
  • simple_lists already contains list<list<u32>> 👻
• record 🚧: Some move semantic mismatch
• option
• result 🚧
  • result_empty is confused about code blocks 👻
  • option_result expected<void, void> has no has_value() 🤔

each in (guest import|export)⨉(argument|result)