Feature/fileinfo create copy (#9198)

* Initial implementation of a CopyFileInfos function that creates new FileInfo objects copied from provided FileIds with the provided user as the creator and not linked to a post yet. This can subsequently be used to copy existing attachments from another post to attach to a new post without having to re-upload the actual files

* added a unit test for the CopyFileInfos function

* resolving pull request suggestions

plugin/client_rpc_generated.go

@@ -1820,6 +1820,36 @@ func (s *apiRPCServer) UpdatePost(args *Z_UpdatePostArgs, returns *Z_UpdatePostR
 	return nil
 }
 
+type Z_CopyFileInfosArgs struct {
+	A string
+	B []string
+}
+
+type Z_CopyFileInfosReturns struct {
+	A []string
+	B *model.AppError
+}
+
+func (g *apiRPCClient) CopyFileInfos(userId string, fileIds []string) ([]string, *model.AppError) {
+	_args := &Z_CopyFileInfosArgs{userId, fileIds}
+	_returns := &Z_CopyFileInfosReturns{}
+	if err := g.client.Call("Plugin.CopyFileInfos", _args, _returns); err != nil {
+		log.Printf("RPC call to CopyFileInfos API failed: %s", err.Error())
+	}
+	return _returns.A, _returns.B
+}
+
+func (s *apiRPCServer) CopyFileInfos(args *Z_CopyFileInfosArgs, returns *Z_CopyFileInfosReturns) error {
+	if hook, ok := s.impl.(interface {
+		CopyFileInfos(userId string, fileIds []string) ([]string, *model.AppError)
+	}); ok {
+		returns.A, returns.B = hook.CopyFileInfos(args.A, args.B)
+	} else {
+		return fmt.Errorf("API CopyFileInfos called but not implemented.")
+	}
+	return nil
+}
+
 type Z_KVSetArgs struct {
 	A string
 	B []byte