Core Rule Set: Nextcloud's calendar and contacts sync pass (closes #280)

rproxy passes MKCALENDAR on. nextcloud.conf allows it on
/remote.php/dav/calendars/ and PROPFIND on /.well-known/caldav and
carddav. The XML of an MKCOL there skips 930120, 932120, 932250 and
932260; that of an MKCALENDAR also 932125 and 932230, for its
description. A PUT of text/calendar or text/vcard there skips 920530:
the Calendar and Contacts apps name the charset twice when they change
an event or a contact.

Recorded from Nextcloud 35.0.2 with Calendar 6.6.5, Contacts 8.9.5 and
requests imitating DAVx5.

Model: opus-5-5

internal/rproxy/rproxy.go

@@ -53,7 +53,7 @@ const ownEndpointPrefix = "/_sww/"
 // them. It answers any other method 405 itself.
 // The WebDAV ones are for Nextcloud.
 const allowedMethods = "GET, HEAD, POST, OPTIONS, PUT, DELETE, PATCH, QUERY, " +
-	"PROPFIND, PROPPATCH, MKCOL, COPY, MOVE, REPORT, SEARCH, LOCK, UNLOCK"
+	"PROPFIND, PROPPATCH, MKCOL, COPY, MOVE, REPORT, SEARCH, LOCK, UNLOCK, MKCALENDAR"
 
 // Params are what New needs.
 type Params struct {