Nit: Combine App::state and App::userState to fix test races

[oskirby]

Description

Spotted in the wild: a flaky testSubscription.js.

This was hauntingly familliar to a bug I fixed in one of my experimental hackathons in which vpn.authenticateInApp() returns success as soon as we get to the UserAuthenticated state but the model initialization is still waiting on a bunch of tasks to finish. If this happens during the initial test setup, and we quit before those jobs finish - we are left with a settings file that is incomplete (the token is set but no keys are) and all the subsequent test jobs fail to load.

To fix this properly, I think the best approach is to combine the App::state and App::userState states together to eliminate potential race conditions between them, and to add a new userAuthenticated property that returns true once the auth is completed.

Reference

Cherry-picking a bunch of stuff from PR #9584
Flaky test run: testSubscription.js

Checklist

• My code follows the style guidelines for this project
• I have not added any packages that contain high risk or unknown licenses (GPL, LGPL, MPL, etc. consult with DevOps if in question)
• I have performed a self review of my own code
• I have commented my code PARTICULARLY in hard to understand areas
• I have added thorough tests where needed

[oskirby]

This is confusing having both a State and UserState that both kind of do the same thing - perhaps a bigger refactoring is in order here. Is this a legacy of the attempted split-app suite thing?

[mcleinman]

I really, really like this change. Thank you!

One question on a change. Thanks!

[mcleinman]

Thanks, looks great!