Before, we were using several IMAP-specific concepts to represent
information being displayed in the UI. Factor these structures out of
the IMAP package to make it easier for other backends to provide the
required information.
Before, the information needed to display different parts of the UI was
tightly coupled to the specific messages being sent back and forth to
the backend worker. Separating out a models package allows us to be more
specific about exactly what a backend is able to and required to
provide for the UI.
The current implementation has three classes of flags:
- readFlag
- delFlag
- flaggedFlag
The logic to check for them should be in parallel if branches rather
than in sequential if-else ladder.
