ReadonlyuploadReadonlyuploadRequest to upload key signatures, including those for the cross-signing keys, and maybe some for the optional uploaded key too.
Should be sent last.
ReadonlyuploadRequest to upload the cross-signing keys.
Should be sent second.
An optional request to upload a device key.
This will either be
undefined, or an "outgoing request" as returned by OlmMachine.outgoingRequests.If it is defined, the request should be sent first, and the result sent back with OlmMachine.markRequestAsSent.