MM-12389 Update segment library to v3 (#11472)

* Update analytics-go dependency

* Migrate from segment library v2 to v3

* Reinclude gorilla/handlers module

* Fix missing module

* Remove reference to outdated analytics module

vendor/github.com/segmentio/analytics-go/group.go

@@ -0,0 +1,40 @@
+package analytics
+
+import "time"
+
+// This type represents object sent in a group call as described in
+// https://segment.com/docs/libraries/http/#group
+type Group struct {
+	// This field is exported for serialization purposes and shouldn't be set by
+	// the application, its value is always overwritten by the library.
+	Type string `json:"type,omitempty"`
+
+	MessageId    string       `json:"messageId,omitempty"`
+	AnonymousId  string       `json:"anonymousId,omitempty"`
+	UserId       string       `json:"userId,omitempty"`
+	GroupId      string       `json:"groupId"`
+	Timestamp    time.Time    `json:"timestamp,omitempty"`
+	Context      *Context     `json:"context,omitempty"`
+	Traits       Traits       `json:"traits,omitempty"`
+	Integrations Integrations `json:"integrations,omitempty"`
+}
+
+func (msg Group) validate() error {
+	if len(msg.GroupId) == 0 {
+		return FieldError{
+			Type:  "analytics.Group",
+			Name:  "GroupId",
+			Value: msg.GroupId,
+		}
+	}
+
+	if len(msg.UserId) == 0 && len(msg.AnonymousId) == 0 {
+		return FieldError{
+			Type:  "analytics.Group",
+			Name:  "UserId",
+			Value: msg.UserId,
+		}
+	}
+
+	return nil
+}