Update the copyright information in all files in the repository

This commit converts the license handling to adhere to the REUSE
specification.  It specifically:

1. Adds used licnses to LICENSES/ directory

2. Add "isc" template for adding the copyright boilerplate

3. Changes all source files to include copyright and SPDX license
   header, this includes all the C sources, documentation, zone files,
   configuration files.  There are notes in the doc/dev/copyrights file
   on how to add correct headers to the new files.

4. Handle the rest that can't be modified via .reuse/dep5 file.  The
   binary (or otherwise unmodifiable) files could have license places
   next to them in <foo>.license file, but this would lead to cluttered
   repository and most of the files handled in the .reuse/dep5 file are
   system test files.

bin/tests/system/include-multiplecfg/ns2/mars.com.db

@@ -1,3 +1,14 @@
+; Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+;
+; SPDX-License-Identifier: MPL-2.0
+;
+; This Source Code Form is subject to the terms of the Mozilla Public
+; License, v. 2.0.  If a copy of the MPL was not distributed with this
+; file, you can obtain one at https://mozilla.org/MPL/2.0/.
+;
+; See the COPYRIGHT file distributed with this work for additional
+; information regarding copyright ownership.
+
 $TTL 86400
 @     IN     SOA    dns1.mars.com.     hostmaster.mars.com. (
                     2001062501 ; serial

bin/tests/system/include-multiplecfg/ns2/mars.conf

@@ -1,3 +1,15 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0.  If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
 
 zone "mars.com" {
         type primary;

bin/tests/system/include-multiplecfg/ns2/named.conf.in

@@ -1,9 +1,11 @@
 /*
  * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
  *
+ * SPDX-License-Identifier: MPL-2.0
+ *
  * This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * License, v. 2.0.  If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
  *
  * See the COPYRIGHT file distributed with this work for additional
  * information regarding copyright ownership.

bin/tests/system/include-multiplecfg/ns2/zone1.com.db

@@ -1,3 +1,14 @@
+; Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+;
+; SPDX-License-Identifier: MPL-2.0
+;
+; This Source Code Form is subject to the terms of the Mozilla Public
+; License, v. 2.0.  If a copy of the MPL was not distributed with this
+; file, you can obtain one at https://mozilla.org/MPL/2.0/.
+;
+; See the COPYRIGHT file distributed with this work for additional
+; information regarding copyright ownership.
+
 $TTL 86400
 @     IN     SOA    dns1.zone1.com.     hostmaster.zone1.com. (
                     2001062501 ; serial

bin/tests/system/include-multiplecfg/ns2/zone1.conf

@@ -1,3 +1,15 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0.  If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
 
 zone "zone1.com" {
         type primary;

bin/tests/system/include-multiplecfg/ns2/zone2.com.db

@@ -1,3 +1,14 @@
+; Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+;
+; SPDX-License-Identifier: MPL-2.0
+;
+; This Source Code Form is subject to the terms of the Mozilla Public
+; License, v. 2.0.  If a copy of the MPL was not distributed with this
+; file, you can obtain one at https://mozilla.org/MPL/2.0/.
+;
+; See the COPYRIGHT file distributed with this work for additional
+; information regarding copyright ownership.
+
 $TTL 86400
 @     IN     SOA    dns1.zone2.com.     hostmaster.zone2.com. (
                     2001062501 ; serial

bin/tests/system/include-multiplecfg/ns2/zone2.conf

@@ -1,3 +1,15 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0.  If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
 
 zone "zone2.com" {
         type primary;