[Web][Tests] Add PHPUnit setup and imapsync module tests

tests/php/bootstrap.php

@@ -0,0 +1,8 @@
+<?php
+
+declare(strict_types=1);
+
+// Production autoloader first: the tests must find the classes through the PSR-4 mapping
+// of data/web/inc/lib/composer.json, exactly as php-fpm does.
+require __DIR__ . '/../../data/web/inc/lib/vendor/autoload.php';
+require __DIR__ . '/vendor/autoload.php';