Wrap the raw pointers exposed across the bridge as named types that approximate
Swift's OpaquePointer?. Parameterize NativeHandleOwner with the native handle
type.
- All public Swift-defined structs except CdsiLookupResponse,
which wraps LookupResponseEntryList, which can *probably* be made
Sendable but I didn't spend time on it.
- All public Swift-defined enums except those being used purely as
namespaces.
- All zkgroup types, since they are immutable and can be serialized
and deserialized to send them anyway
- ServiceId and its subclasses, an immutable class hierarchy
- ProtocolAddress, PinHash, SenderCertificate and ServerCertificate,
and all public and private Key types, immutable wrappers around
immutable Rust objects
More of our wrapper types could be made Sendable as well if there's a
need to. See CODING_GUIDELINES for more info.
