Introduce simple monitoring bus

Description

This patch introduce a monitoring bus that collects and streams structured protobuf messages in an asynchronous fashion.

Changes proposed in this merge request:

• Define internal protobuf message structure for monitoring.
• Move event loop handling into server's main class.
• Introduce a monitoring bus that integrate with the min loop.
• Update tests to main loop handling change.

This merge request, when merged, will address issue/bug:

#135 (closed)