MM-49486: Option to exclude file count in channel stats (#22096)

Co-authored-by: Mattermost Build <build@mattermost.com>

model/client4.go

@@ -3032,8 +3032,9 @@ func (c *Client4) GetChannel(channelId, etag string) (*Channel, *Response, error
 }
 
 // GetChannelStats returns statistics for a channel.
-func (c *Client4) GetChannelStats(channelId string, etag string) (*ChannelStats, *Response, error) {
-	r, err := c.DoAPIGet(c.channelRoute(channelId)+"/stats", etag)
+func (c *Client4) GetChannelStats(channelId string, etag string, excludeFilesCount bool) (*ChannelStats, *Response, error) {
+	route := c.channelRoute(channelId) + fmt.Sprintf("/stats?exclude_files_count=%v", excludeFilesCount)
+	r, err := c.DoAPIGet(route, etag)
 	if err != nil {
 		return nil, BuildResponse(r), err
 	}