oc-calendar: Enable editor role

When Outlook sets the editor role, the FreeBusyDetailed and FreeBusySimple
right flags are set as Full Details are available.

When we store this information in SOGo, the SOGoCalendarRole_PublicModifier,
SOGoCalendarRole_PrivateModifier and SOGoCalendarRole_ConfidentialModifier
are stored as well as the free busy related roles, but as
[SOGoAppointmentFolder aclsForUser:forObjectAtPath] only returns the highest
access rights, we have to set as well the FreeBusy flags.

More details on [MS-OXCPERM] Section 2.2.6