Migrate to new authentication infrastructure

[benjumanji]

• Move away from auth0 prop grant to oauth2 resource owner password grant.
• Point at new hypervolt authentication infrastructure.
• Audience is not required, as it is mapped based on the client.

[benjumanji]

@gndean can you do me a favour: I am not by any means a python expert. I would have expected, based on my brief reading of https://docs.aiohttp.org/en/stable/client_quickstart.html#more-complicated-post-requests that this auth request would be sending form encoded data. If it isn't that would explain the 400.

[gndean]

Yes, it's form encoded. Here's what the raw HTTP request looks like:

Host: auth.hypervolt.co.uk
user-agent: home-assistant-hypervolt-charger/2.0.1
Accept: */*
Accept-Encoding: gzip, deflate
Content-Length: 370
Content-Type: application/x-www-form-urlencoded

audience=https%3A%2F%2Fapi.hypervolt.co.uk&client_id=1BfAeDNKfu7mfPWCm6XTsZeM2QYhhju2&grant_type=http%3A%2F%2Fauth0.com%2Foauth%2Fgrant-type%2Fpassword-realm&realm=Username-Password-Authentication&scope=openid+profile+email+offline_access&username=...

[benjumanji]

So I would hope that the new request then would roughly correspond with

❯ curl --request POST 'https://kc.prod.hypervolt.co.uk/realms/retail-customers/protocol/openid-connect/token' \
      --header 'Content-Type: application/x-www-form-urlencoded' \
      --data-urlencode 'client_id=home-assistant' \
      --data-urlencode 'password=XXX' --data-urlencode 'username=XXX' \
      --data-urlencode 'grant_type=password'
{"access_token":"XXX","expires_in":3600,"refresh_expires_in":5400,"refresh_token":"XXX","token_type":"Bearer","not-before-policy":1711661767,"session_state":"XXX","scope":"profile social email"}

I mean feel free to test with your own username and password. Maybe I am missing some url encoding of the params?

[gndean]

OK, so using the domain kc.prod.hypervolt.co.uk, not kc.hypervolt.co.uk, as in this PR, is working. I did guess this and thought I had tried it previously and received a 400 but I must have changed something else at the same time.

Also, should the client_id be "home-assistant" or "native-with-token-exchange"?

~Can you update the PR to include this correct domain name please. Then I can retest and hopefully merge.~ Edit: Sorry, I missed the updated commit from yesterday with the corrected domain name.

I'll retest now, with a view to merging.