3.3 SNAPSHOT: AuthN resolveAttribute not activating authn flow

[Cantor, Scott]

> I think this is the change involved:
> 
> https://issues.shibboleth.net/jira/browse/IDP-980

I've reverted most of the changes I made for that issue after reconsidering them and fixed the IsPassive problems I had identified with a different solution. I believe this should fix the regression with attribute-based filtering of flows.

Please re-test with a nightly snapshot within the next week or so if you can.

The main reason I'm emphasizing a different approach to this probem is that there's no flow filtering going on when the MFA feature is used. I went back and forth but where it ended up is that you don't actually enable a bunch of different flows to use with it, you just enable MFA alone. So there's nothing to filter, it's left to the MFA workflow to decide what to run; but, when you come back in later, the system will just reuse that result unless you manipulate the RequestedPrincipalContext to prevent it (or if the SP just requests something else).

So I guess the summary is:

I believe I've restored the 3.2 behavior when the approach is to juggle a bunch of methods and do filtering to control when they're used.

They don't really work with the MFA feature by design.
 
The approaches to manage things that do work with the MFA feature also work better than the filtering of flows did before, even if the MFA feature isn't actually being used, but I'll have to build some examples to illustrate that.

-- Scott