- 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.
This is very similar to the AuthCredential used by the group server,
but using CallLinkParams to encrypt the user ID rather than
GroupParams (and using GenericServerParams to issue the credential
rather than the group server's ServerParams).
