[TCPContainer] Test if connection to agents should be kept open

[rcschrg]

In GitLab by @mnebel-wenner on Dec 1, 2022, 11:01

When a TCPContainer sends a message, it right now creates a connection to the receiving agent via create_connection(), then transfers the data and then closes the connection again. It could however be possible to keep the connection open to other agents (maybe until some time withou a message having be sent). This might speed-up the message transfer as connections do not have to bee established all the time.