OAuth2 API feedback

[dotMorten]

Started to try and use the 1.7exp1 OAuth APIs and got a little bit of feedback.

I must have missed this in the earlier design review, but now seeing this:

This took me a while to discover that I had to do this, and only because as the author of WinUIEx, I have the same requirement in my library, and it's not a fun requirement to have, as I know from experience it has tripped up a lot of users. My hope was that the Windows Apps SDK could solve this at a lower level and not have this same pitfall.

Secondary the example isn't great. It is better to do this in the static main before the application fully starts up, so you don't have to do the forced termination. Perhaps a simple solution could be to just have this be a standard part of the auto-generated main?

Lastly, my app hangs after calling CompleteAuthRequest and VS shows me this message shortly later:

Without the debugger attached the process just hangs for quite a while before shutting down.

[dotMorten]

One additional feedback item that a customer just reported in WinUIEx: Relying on the state parameter can have problems with some OAuth services. See dotMorten/WinUIEx#195 (comment)
I see that this API uses the same trick as WinUIEx to rely on roundtripping the state parameter to resume the correct process.