We need to ensure that we recurse into the auxiliary decls in
`enumerateStoredPropertiesAndMissing` to pick up properties in
nested macro expansions. Also do the same in
`enumerateCurrentPropertiesAndAuxiliaryVars` and
`InitializablePropertiesRequest` to ensure the memberwise initializer
correctly handles this case. This would technically be ABI breaking,
but previously we would have just crashed in SILGen.
rdar://166908960
48464a9cbd