standardizes the calendar resolver interface

Adds a little extra process into the calendar
resolver so that it mimics the mail and contact
resolvers.  This will allow us to collapse the
three resolvers into a more common handler
or interface.

src/internal/connector/exchange/event_calendar_cache.go

@@ -84,6 +84,10 @@ func (ecc *eventCalendarCache) Populate(
 		return errors.Wrap(err, "establishing calendar paths")
 	}
 
+	if err := ecc.populatePaths(ctx); err != nil {
+		return errors.Wrap(err, "establishing calendar paths")
+	}
+
 	return nil
 }