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/MPL2.txt

@@ -0,0 +1,12 @@
+Mozilla Public License Version 2.0
+
+Copyright (c) YEAR AUTHOR
+
+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/.
+
+If it is not possible or desirable to put the notice in a particular
+file, then You may include the notice in a location (such as a LICENSE
+file in a relevant directory) where a recipient would be likely to look
+for such a notice.