Disable SyncException triggered by folder name change.

Summary:
There's not really any reason why we shouldn't just... update the folder
to the new name. This occurs when e.g. users on Gmail change their
locale. And as far as I can tell, never otherwise. We expect the backend
account provider to return the correct mapping if the name changes,
rather than us bailing out here and not handling the case.

Tags are named by `canonical_name`, so they do not need to be updated
when the folder name changes as long as the folder row remains the same
(same id).

Fixes T4.

Test Plan:
Manually changed locale in Gmail UI for locally syncing account, verified
folders list, changed back, verified folders list again. Also manually verified
that logic for dealing with "dangled" Gmail IMAP folders (core folders which
have been disabled via the "Show in IMAP" checkbox) still works.

Reviewers: khamidou

Maniphest Tasks: T4

Differential Revision: https://review.inboxapp.com/D553