MM-27493 Shared channels (MVP) (#17301)

Remote Cluster Service
- provides ability for multiple Mattermost cluster instances to create a trusted connection with each other and exchange messages
- trusted connections are managed via slash commands (for now)
- facilitates features requiring inter-cluster communication, such as Shared Channels
Shared Channels Service
- provides ability to shared channels between one or more Mattermost cluster instances (using trusted connection)
- sharing/unsharing of channels is managed via slash commands (for now)

store/layer_generators/main.go

@@ -270,18 +270,23 @@ func generateLayer(name, templateFile string) ([]byte, error) {
 		"joinParams": func(params []methodParam) string {
 			paramsNames := make([]string, 0, len(params))
 			for _, param := range params {
-				paramsNames = append(paramsNames, param.Name)
+				tParams := ""
+				if strings.HasPrefix(param.Type, "...") {
+					tParams = "..."
+				}
+				paramsNames = append(paramsNames, param.Name+tParams)
 			}
 			return strings.Join(paramsNames, ", ")
 		},
 		"joinParamsWithType": func(params []methodParam) string {
 			paramsWithType := []string{}
 			for _, param := range params {
-				if param.Type == "ChannelSearchOpts" || param.Type == "UserGetByIdsOpts" {
+				switch param.Type {
+				case "ChannelSearchOpts", "UserGetByIdsOpts":
 					paramsWithType = append(paramsWithType, fmt.Sprintf("%s store.%s", param.Name, param.Type))
-				} else if param.Type == "*UserGetByIdsOpts" {
+				case "*UserGetByIdsOpts":
 					paramsWithType = append(paramsWithType, fmt.Sprintf("%s *store.UserGetByIdsOpts", param.Name))
-				} else {
+				default:
 					paramsWithType = append(paramsWithType, fmt.Sprintf("%s %s", param.Name, param.Type))
 				}
 			}
@@ -290,11 +295,12 @@ func generateLayer(name, templateFile string) ([]byte, error) {
 		"joinParamsWithTypeOutsideStore": func(params []methodParam) string {
 			paramsWithType := []string{}
 			for _, param := range params {
-				if param.Type == "ChannelSearchOpts" || param.Type == "UserGetByIdsOpts" {
+				switch param.Type {
+				case "ChannelSearchOpts", "UserGetByIdsOpts":
 					paramsWithType = append(paramsWithType, fmt.Sprintf("%s store.%s", param.Name, param.Type))
-				} else if param.Type == "*UserGetByIdsOpts" {
+				case "*UserGetByIdsOpts":
 					paramsWithType = append(paramsWithType, fmt.Sprintf("%s *store.UserGetByIdsOpts", param.Name))
-				} else {
+				default:
 					paramsWithType = append(paramsWithType, fmt.Sprintf("%s %s", param.Name, param.Type))
 				}
 			}