Add popular open-source license templates

Add eight license templates:
- Apache2.txt: Apache License 2.0
- BSD2.txt: BSD 2-Clause License
- BSD3.txt: BSD 3-Clause License
- GPLv2.txt: GNU General Public License v2
- ISC.txt: ISC License
- LGPL.txt: GNU Lesser General Public License v3
- MIT0.txt: MIT No Attribution License (0-Clause MIT)
- MPL2.txt: Mozilla Public License v2.0
- Unlicense.txt: Unlicense (public domain)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

licenses/Apache2.txt

@@ -0,0 +1,16 @@
+Apache License
+Version 2.0, January 2004
+
+Copyright (c) YEAR AUTHOR
+
+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.