OIDC Device Flow with extra variables

[smira]

Allow talos.config= flow for metal platform to use OIDC device auth flow to acquire the machine configuration.

We might want to have a lightweight implementation, great overview.

talos.config= will be parsed to get the base hostname for OAuth API.

We need following input params:

• client_id (mandatory)
• audience
• scopes
• extra variables to send with the request, out of those available in talos.config URL interpolation, e.g. uuid

Proposal:
talos.config.oidc.client_id=foo talos.config.oidc.audience=world talos.config.oidc.scopes=auth talos.config.oidc.extra_variables=uuid,mac

Once the URL & user_code are available, show it in the console, plus show the QR (library).

We can print QR & URL, user_code to the console. Plus if the dashboard is running, we can use it to show the QR, we need some integration e.g. via resources.

Keep polling OAuth until we get the token or failure.

Once the token is acquired, fetch machine config with token using regular flow via talos.config=.