MM-11781: Basic Data Export Command Line. (#9296)

* MM-11781: Basic Data Export Command Line.

* ChannelStore new unit tests.

* TeamStore new unit tests.

* Unit test for new UserStore function.

* Unit tests for post store new methods.

* Review fixes.

* Fix duplicate command name.

model/channel.go

@@ -57,6 +57,12 @@ type ChannelPatch struct {
 	Purpose     *string `json:"purpose"`
 }
 
+type ChannelForExport struct {
+	Channel
+	TeamName   string
+	SchemeName *string
+}
+
 func (o *Channel) DeepCopy() *Channel {
 	copy := *o
 	if copy.SchemeId != nil {