Onboarding view controller needs to set the account info object on the
mastodon controller before calling getOwnAccount since getOwnAccount
will upsert the user's account into the persistent container, which
requires the account info to exist to create a unique-per-account
identifier.
When loading a draft:
If the draft was created from a different account than the current one:
If the draft was in reply to a status, don't allow it to be loaded.
If the draft was not in reply to a status, prompt the user whether
or not to load the draft.
If the draft was in reply to a different status than the current one:
Prompt the user whether or not to load the draft.
Otherwise, load the draft.
Draft replies created from other accounts can't be loaded from different
accounts because the status for inReplyToID of the draft will have a
different instance-local ID if the two accounts are on different
instances.
See #16
Shadowfacts