Webhooks: Fixed failing delete-based events

Due to queue serialization.
Added a test to check a couple of delete events.
Added ApiTokenFactory to support.
Also made a couple of typing/doc updates while there.

Related to #4373

database/factories/Api/ApiTokenFactory.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace Database\Factories\Api;
+
+use BookStack\Api\ApiToken;
+use BookStack\Users\Models\User;
+use Illuminate\Database\Eloquent\Factories\Factory;
+use Illuminate\Support\Carbon;
+use Illuminate\Support\Str;
+
+class ApiTokenFactory extends Factory
+{
+    protected $model = ApiToken::class;
+
+    public function definition(): array
+    {
+        return [
+            'token_id' => Str::random(10),
+            'secret' => Str::random(12),
+            'name' => $this->faker->name(),
+            'expires_at' => Carbon::now()->addYear(),
+            'created_at' => Carbon::now(),
+            'updated_at' => Carbon::now(),
+            'user_id' => User::factory(),
+        ];
+    }
+}