SEP-990: investigate support for enterprise IdP policy controls extension

[findleyr]

Investigate if we can/should implement support for SEP-990, and enterprize auth flow. This is an MCP extension.

[radar07]

@findleyr I'd like to work on this since my team is working on implementing this in other SDKs

[findleyr]

@radar07 that would be great. I'm not sure exactly how we'll approach SDK extensions, but if you want to map out this change, we can help figure out how to integrate it into the SDK.

[radar07]

@findleyr This is the plan I'm going far and I've been working on a test PR. Let me know if you any other ideas for this one.