simplified checkout event handling per @uberbrady’s suggestion

This generalizes the checkout events into the CheckoutableCheckedOut and CheckoutableCheckedIn events.

app/Events/CheckoutableCheckedIn.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace App\Events;
+
+use App\Models\User;
+use Illuminate\Foundation\Events\Dispatchable;
+use Illuminate\Queue\SerializesModels;
+
+class CheckoutableCheckedIn
+{
+    use Dispatchable, SerializesModels;
+
+    public $checkoutable;
+    public $checkedOutTo;
+    public $checkedInBy;
+    public $note;
+
+    /**
+     * Create a new event instance.
+     *
+     * @return void
+     */
+    public function __construct($checkoutable, $checkedOutTo, User $checkedInBy, $note)
+    {
+        $this->checkoutable = $checkoutable;
+        $this->checkedOutTo = $checkedOutTo;
+        $this->checkedInBy  = $checkedInBy;
+        $this->note         = $note;
+    }
+}