Import: Selection of calendars only with todo lists - info/warning why

Is your feature request related to a problem? Please describe.

When importing an ics file into a calendar, sometimes not every calendar is displayed for selection.
After some research, this only happens if todo lists are included in the ics file. Then only the calendars that also have a todo list are displayed, if there are any.

Describe the solution you'd like

At this point it would be good to know why only certain calendars are displayed, as this can otherwise lead to confusion.
So simply a sentence indicating that the ics file contains todo list entries and therefore only calendars with todo lists for import are displayed

Describe alternatives you've considered

Alternatively, you can still specify all calendars for the import with the note that toto lists may be lost

Additional context

No response

The issue does not name files or tests. Start by tracing the ICS import calendar-selection UI and how files containing todo-list entries are handled. Add a clear explanation when only calendars supporting todo lists are shown, then verify the message during an import of an ICS file containing todo entries.