move connector + connection config

src/ConnectionConfig.php

@@ -0,0 +1,7 @@
+<?php
+
+namespace Amp\Sql;
+
+interface ConnectionConfig {
+    public function connectionString(): string;
+}

src/Connector.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace Amp\Sql;
+
+use Amp\Promise;
+
+interface Connector {
+    /**
+     * @param ConnectionConfig $config
+     *
+     * @return Promise<Connection>
+     */
+    public function connect(ConnectionConfig $config): Promise;
+}