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/ISC.txt

@@ -0,0 +1,15 @@
+ISC License
+
+Copyright (c) YEAR AUTHOR
+
+Permission to use, copy, modify, and/or distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.