feat: implement caldav search

vendor/github.com/dolanor/caldav-go/caldav/entities/multistatus.go

@@ -0,0 +1,23 @@
+package entities
+
+import "encoding/xml"
+
+// metadata about a property
+type PropStat struct {
+	XMLName xml.Name `xml:"propstat"`
+	Status  string   `xml:"status"`
+	Prop    *Prop    `xml:",omitempty"`
+}
+
+// a multistatus response entity
+type Response struct {
+	XMLName   xml.Name    `xml:"response"`
+	Href      string      `xml:"href"`
+	PropStats []*PropStat `xml:"propstat,omitempty"`
+}
+
+// a request to find properties on an an entity or collection
+type Multistatus struct {
+	XMLName   xml.Name    `xml:"DAV: multistatus"`
+	Responses []*Response `xml:"response,omitempty"`
+}