Add correct license header to main-1.0.0

[fpj]

What went wrong?

Fixing the license headers in main-1.0.0. This PR is replacing:

/*
 * Copyright 2021 Qbeast Analytics, S.L.
 */

with

 /*
 * Copyright 2021 Qbeast Analytics, S.L.
 *
 * 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,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

[osopardo1]

No longer needed, merged main-1.0.0 to main in https://github.com/Qbeast-io/qbeast-spark/pull/284