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.
In a future release ProtocolAddresses will *only* support ServiceIds,
so these APIs are designed to be the nullable version of the signature
they'll eventually have. Since ProtocolAddresses are created by the
client app in nearly all cases, they should be able to ignore the null
case if they only use ServiceIds in their input.
