Isolated the JsonServer to server.py inside protocols/json
Added specific errors for server startup timeout and server startup
failed
Refactored errors for Core to CoreError generic and refactored
StateError to CoreStateMismatchError derived from CoreError
Completed the initial implementation of the JsonServer class, handling
the worker thread that runs the async task, as well as the connection
handler callback
The current handler awaits readline to cleanly exit when the connection
is closed, no data ingress is happening yet
Next steps include gating the start procedure to wait for everything to
start proprerly in order to avoid having start exit early and async
tasks crashing later
h3cx