uplift(beta): enforce always one outbox folder per account and remove outboxFolderId from preferences

[rafaeltonholo]

This PR uplifts #9852 to beta, enforcing the app to always have an Outbox folder

[thunderbird-botmobile]

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[Approval Request]
Original Issue/Pull request: #8049/#9852
Regression caused by (issue #): #9710 and #9772 (Not really those issues, but apparently they increased the change of the issue to happen)
User impacts if declined: Users might see the "IllegalStateException: No outbox_state entry for message with id " annoying notification, as the Outbox might got deleted and the Inbox folder is set as the Outbox
Testing completed (on daily, etc.): debug
Risk to taking this patch (and alternatives if risky): Although it is unlikely to happen, users may have multiple entries for the Outbox in their database, but the app will select the one with the type set to "outbox" and use it as the outbox folder.