CardDAV/CalDAV sync add modify with OSX/IOS/Android etc.

[nikor30]

Version in use Version: 4.1.2 via Docker container

Raising up a feature which would be great to use Monica also as a full Calendar and Contacts Backend for IOS and other platforms.

The DAV implementation needs to be opened, so Monica is usable also on Mobile devices on their native APS.

Also, if there is an easier way to add LDAP or other ways to snync is welcome