Tasks/todos (and maybe notes/journals) in jmap-webmail?

[chhaas]

It would be a great enhancement for jmap-webmail, if it would also support tasks/todos.
This should be doable with less effort, since tasks are VTODOs in CalDAV.

An outstanding feature would be, if also notes and journals (CalDAV VJOURNAL) would be supported, since no other webclient I know support this at the moment.

Both tasks (VTODO) and notes/journals (VJOURNAL) are specified alongside with VEVENT for calendar in the iCalendar RFC 5545 (https://datatracker.ietf.org/doc/html/rfc5545).

Sync with e.g. Techbees JTXboard (Android) with DAVx5 (Android)