Support Event Messages

[Poofjunior]

As is, pyharp assumes a request-reply interface between PC and Harp device where messages strictly follow a PC-issued request. In reality, the Harp protocol defines a spec for "event" messages issued from pc-to-device at any time, and the current pyharp package breaks if any of these "event" messages are sent. Accommodating the asynchronous part of the protocol into the pyharp package makes it fully-compliant with Harp protocol.

References:

• https://github.com/AllenNeuralDynamics/pyharp
• https://www.enterpriseintegrationpatterns.com/patterns/conversation/RequestResponse.html
• https://github.com/AllenNeuralDynamics/harp.device.rp2040-template