API from Firerunner to VM for managing local FS over vsock

[pisimulation]

• Firerunner listens to incoming vsock connection in a separate thread.
• c-vsock/ is a bash runtime with vsock client in workload.c compiled with gcc
• VM and Firerunner talk to each other by just dumping bytes over vsock.
• VM ends each op with a \r (carriage return) character
• Firerunner handles a stream of ops by splitting each op by \r and, for each op, separates parameters by the null character.