[tq] Move to top-level package.

appengine/tq/tq.go

 // Copyright 2017 The LUCI Authors.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //      http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 396 matching lines @@
                 return nil, fmt.Errorf("no task body given")
         }
 
         task := reflect.New(tp.Elem()).Interface().(proto.Message)
         if err := jsonpb.Unmarshal(bytes.NewReader(*env.Body), task); err != nil {
                 return nil, err
         }
 
         return task, nil
 }