Add captcha tokens management.

app/Contracts/GenerateTokenCommand.php

@@ -0,0 +1,11 @@
+<?php declare(strict_types=1);
+
+namespace App\Contracts;
+
+use Illuminate\Database\Eloquent\Builder;
+
+interface GenerateTokenCommand
+{
+    public function execute(): string;
+    public function unique(Builder $builder, string $field, int $numberAttempts = 10): string;
+}