Missing CalDAV server features

[DeepDiver1975]

Background

I am running https://github.com/apple/ccs-caldavtester against go-webdav and listing missing features.
Leaving these findings for now and will open pull requests every now and then as time permits.

RFCs

• RFC6638 - Scheduling Extension for CalDAV - https://datatracker.ietf.org/doc/html/rfc6638
• RFC6578 - Collection Synchronization - https://datatracker.ietf.org/doc/html/rfc6578

[emersion]

RFC 6578 is tracked in #35 and we have CardDAV client support.