Implement support for the new authorization specification

[localden]

Is your feature request related to a problem? Please describe.

Implement support for the draft authorization specification that was merged earlier last month.

Describe the solution you'd like

Implement supoprt for RFC9728, along with other requirements outlined in the spec.

Describe alternatives you've considered

N/A

Additional context

• C# implementation: Authorization Support (Using ASP.NET Core Native AuthN/AuthZ Integration) csharp-sdk#377

[felixweinberger]

Relatively old issue, need to confirm whether this may have already been implemented potentially as part of one of these https://github.com/modelcontextprotocol/python-sdk/pulls?q=is%3Apr+9728+is%3Aclosed