add public connection() method to the Tenant DB manager interface

src/Database/Contracts/StatefulTenantDatabaseManager.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace Stancl\Tenancy\Database\Contracts;
+
+use Illuminate\Database\Connection;
+use Stancl\Tenancy\Database\Exceptions\NoConnectionSetException;
+
+/**
+ * Tenant database manager with a persistent connection.
+ */
+interface StatefulTenantDatabaseManager extends TenantDatabaseManager
+{
+    /** Get the DB connection used by the tenant database manager. */
+    public function database(): Connection; // todo rename to connection()
+
+    /**
+     * Set the DB connection that should be used by the tenant database manager.
+     *
+     * @throws NoConnectionSetException
+     */
+    public function setConnection(string $connection): void;
+}