[neohub] Add support for WebSocket connection to hub

[andrewfg]

Heatmiser has released their API specification v3.0 (it is dated 12/12/2021 but was actually uploaded to their developer portal today).

In this new release Heatmiser announce the following..

• New support for discovery of NeoHub devices via UDP LAN broadcast
• New support for certificate authenticated and encrypted connection to the NeoHub via WSS WebSockets
• Existing (legacy) plain socket connection continues to be supported, albeit disabled by default - see [neohub] Workaround for 'Legacy API Disabled' problem #12906

I am planning to add support for these new features to the OpenHAB NeoHub binding (already working on it).
Specifically the following features will be added..

1. Add an auto discovery service for NeoHub devices.
2. Add support for WSS WebSocket connection; the choice of websocket vs. plain socket to be via an OH config param.

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EDIT: in case anyone needs further background see the following links..

• Heatmiser API Specification v3.0
• Heatmiser Developer Portal thread