Add finalisation support to the Management Agent API
Strip out test modules since relocated to distributed-process-tests
Refactor (simplify)
Allow Management Agents to utilise their mailbox

Previously, management agents only processed messages delivered over
a broadcast TChan, duplicated from the primary management event bus.
To facilitate sending messages to a specific agent (and not the entire
event processing subsystem) and reduce load on other agents (and the
event bus itself), we perform a non-blocking read on the agent’s own
mailbox whenever its input channel is empty.
Management API Improvements

* Agents can choose to prioritise the mailbox over the event bus
* Event sinks can be “skipped”
* Added a local state update API
* Additional Documentation
Fix a nasty memory leak in the management infrastructure

Previously, the management event bus could fill up with data that
never got GC’ed, since no consumer (of the event bus) was guaranteed
to exist. Introducing a “dead letter consumer” that continuously
reads from the channel, ensures that even when no management agents
are installed on a node, we still dequeue all MxEvents and thereby
avoid leaking space.
Improve Management API Documentation