Make enclave server async

[emostov]

The enclave server should be async so

• it can proxying requests to a secure app
• the phase can be checked while its executing other processes

[emostov]

Once we make the server async, it will be important to ensure we are properly updating protocol phase mid request handling.

For example if we get the Kth provision request, we should lock state to ensure we don't simultaneously accept the K+1 provision request in the middle of trying to reconstruct secret.

[emostov]

In order to prove this works we should create the status endpoint and show we can query the status endpoint while doing some other slow op