[Feature] Reverse agent connection

[AndreKR]

Currently the periphery agent needs to be reachable and have valid TLS certificates so that the server can connect to the agent.

If the agent could connect to the server instead, Komodo would be able to manage devices that do not provide a web server (or any server at all).

It would also simplify certificate management because only the server would need to have valid TLS certificates, not every agent.

This is related to #123 and #147.

[mbecker20]

Yes I have considered this and agree, I was planning this for Komodo v2 (it would definitely be breaking change for existing users). The idea is the Periphery agent is given a Core endpoint and an identity token generated by Core unique to each server. Then they will persist outbound websocket connection to Core to achieve duplex communication.