Restore Initial Meaningful Test Infrastructure

This testing package was initially a part of flarum/core, but was
extracted during the 0.1.0-beta.16 release cycle. The extraction was
made through git's filter-branch tool to preserve some useful history in
the repository.

php-packages/testing/tests/integration/tmp/vendor/composer/installed.json

@@ -0,0 +1 @@
+{}