Support for Tesla HTTP Proxy

[llamafilm]

Since Tesla has deprecated the Owner API, I believe the easiest path to keep using this library (and the Home Assistant integration that depends on it) is to use Tesla's HTTP Proxy. I've built a Home Assistant add-on that does exactly this, plus it handles the initial authorization flow which is somewhat complicated. Since it's completely self-hosted, it does not require trusting any third party with your credentials. And we can still benefit from the new public key security model.

I haven't yet had time to test with this library, but I believe it only requires 3 changes:

• optional custom API_URL
• optional custom SSL certificate (because the HTTP proxy is not publicly accessible)
• optional custom refresh token

Add-on is here: https://github.com/llamafilm/tesla-http-proxy-addon

[purcell-lab]

Great work!

[alandtse]

We'll welcome the PR when it's provided.

[alandtse]

closed by #454