Add keep-alive response monitoring and automatic reconnection
Background: issue reported from customer: XMPP connection hang when uplink is dropped https://project.iopsys.eu/issues/15129
Implemented:
Implemented a mechanism to monitor missed keep-alive responses and automatically reconnect the XMPP session when a specified maximum is exceeded.
Added UCI option max_keepalive_fails
, if not specified in the config, defaults to 0,
which means the feature is disabled by default.