Guided Tours: Bail if fresh user prefs missing

[mcsf]

The Guided Tours framework tracks which tours a user has seen (completed or dismissed) by persisting that history using the Preferences API (state.preferences). Up to this point, it was missing an explicit check that the preferences available locally (via getPreferences) have been successfully pulled from the server and aren't stale. Without the check, GT assumed the history was empty (and thus any tour was good to show again). The check should guard against two issues:

• In the case where Guided Tours runs before the request for fresh preferences (typically in order to satisfy a <QueryPreferences /> element), we ensure that GT waits for the preferences before deciding on a tour. [fig 1]
• In the case where something is consistently failing between the user and the preferences endpoint (e.g. users with 2-factor authentication enabled and a stale token, see Framework: Account for Preferences settings 2FA refresh response #202), Guided Tours will defensively not run at all. [fig 2]

fig 1:

fig 2:

To test

The best is likely to locally revert #10706, set localStorage.setItem( 'debug', 'calypso:guided*' ) and test with different accounts (without 2FA, with 2FA and fresh token, with 2FA and stale token) and different histories (having seen editorInsertMenu, having not seen it).

[matticbot]

Test live: https://calypso.live/?branch=fix/guided-tours-bail-if-stale-prefs

[lsinger]

Testing revealed that the change works mostly as intended, but that it also keeps tour from starting that are forced using a query argument. Therefore, 0e9e146 moves the bailing code to the findTriggeredTour function. @marekhrabe can you review when @mcsf has fixed the failing test suite 😬?

To make the token stale, delete the twostep_auth cookie from the public-api.wordpress.com domain.

[mcsf]

Test suite amended, approval requested, @lsinger and @marekhrabe :)

[marekhrabe]

I tested with token cookie removed and this PR worked as expected.

[marekhrabe]

👍