refactor: ./tests (#2649)

* refactor: ./tests

* test: consolidate testsuites

* refactor: move config setup into rssbridge.php

Makes it easier to unit test.

* lint

tests/CacheImplementationTest.php

@@ -1,5 +1,4 @@
 <?php
-require_once __DIR__ . '/../lib/rssbridge.php';
 
 use PHPUnit\Framework\TestCase;