[MM-16934] Add API endpoint to update channel privacy (#11993)

* Add API endpoint to update channel privacy setting

* Fix language files

* Improve tests by making sure channel has been updated correctly

* Improve tests

model/client4.go

@@ -2100,6 +2100,17 @@ func (c *Client4) ConvertChannelToPrivate(channelId string) (*Channel, *Response
 	return ChannelFromJson(r.Body), BuildResponse(r)
 }
 
+// UpdateChannelPrivacy updates channel privacy
+func (c *Client4) UpdateChannelPrivacy(channelId string, privacy string) (*Channel, *Response) {
+	requestBody := map[string]string{"privacy": privacy}
+	r, err := c.DoApiPut(c.GetChannelRoute(channelId)+"/privacy", MapToJson(requestBody))
+	if err != nil {
+		return nil, BuildErrorResponse(r, err)
+	}
+	defer closeBody(r)
+	return ChannelFromJson(r.Body), BuildResponse(r)
+}
+
 // RestoreChannel restores a previously deleted channel. Any missing fields are not updated.
 func (c *Client4) RestoreChannel(channelId string) (*Channel, *Response) {
 	r, err := c.DoApiPost(c.GetChannelRoute(channelId)+"/restore", "")