[Session] Fix stale emailAuthFactor and emailConfirmed on the client

[gaearon]

Extracted from #3728. The fix is b0aa70d.

The intent of this code was to use the value from the session and fallback to the stored value if the session isn't present. However, if session.emailAuthFactor (newer) is false but account.emailAuthFactor (older) is true, the session?.emailAuthFactor || account.emailAuthFactor expression will keep giving us true even though false is the fresh value here. So we'll store and display the incorrect stored true value.

The fix is to use ?? instead. I've updated a few other places we use || for fallback values for consistency in the second commit, but that shouldn't affect the behavior.

Test Plan

To trigger this, you'd need to get a "session changed" event from the agent with the new session info. One way you can get there is by having your token expired. I don't know how to make that happen though.

A simpler way to trigger it is to comment out these lines so that resumeSessionWithFreshAccount() itself starts, but then we're rely on the logic in onAgentSessionChange to actually apply the update.

Then the test plan becomes:

1. Switch to main and comment out the lines mentioned above
2. In another browser window, open prod and turn on 2FA in Settings
3. Refresh browser locally, observe that 2FA flag is on in Settings
4. In another browser window, open prod and turn off 2FA in Settings
5. Refresh browser locally, observe that 2FA flag is still on in Settings
6. Refresh browser locally, observe that 2FA flag is still on in Settings
7. Switch to this branch and comment out the lines mentioned above
8. Refresh browser locally, observe that 2FA flag is off in Settings, as expected

From that point on, toggling it off and on in another browser window is correctly applied on session refresh.

[render]

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Follow its progress at https://dashboard.render.com/web/srv-coq42o8l6cac73bu44s0.

[github-actions]

Old size	New size	Diff
6.86 MB	6.86 MB	64 B (0.00%)

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