feat: Add basic client and first basic endpoint

Adds the client with first basic authentication and
the first endpoint `repositories` with first method.

Classes/Endpoint/EndpointInterface.php

@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Avency\Gitea\Endpoint;
+
+use Avency\Gitea\Client;
+
+/**
+ * Endpoint interface
+ */
+interface EndpointInterface
+{
+}