Make feedback to know when client is busy

[goldarte]

Request description
When we send any command or file, we don't know what happens with client, only telemetry stops to transmit. So we need to think about the way to know the feedback from copter during some tasks and operations.

[artem30801]

Possible solutions: display blocking operations in System col or/and make Connection state column with possible states: disconnected, idle, reading, writing, readwrite

[goldarte]

Why telemetry sending loop stop sending telemetry when file is transmitting to client, for example? Because connection manager works in one thread, and can only send or get message at time. Can we make different threads/connections for input and output messages?