[1.7.0] Add Events system (#93)

* Add TenantManagerEvents

* Apply fixes from StyleCI

* Fix typos, add tests

* end() events

src/Traits/TenantManagerEvents.php

@@ -0,0 +1,70 @@
+<?php
+
+namespace Stancl\Tenancy\Traits;
+
+trait TenantManagerEvents
+{
+    /**
+     * Event listeners.
+     *
+     * @var callable[][]
+     */
+    protected $listeners = [
+        'bootstrapping' => [],
+        'bootstrapped' => [],
+        'ending' => [],
+        'ended' => [],
+    ];
+
+    /**
+     * Register a listener that will be executed before tenancy is bootstrapped.
+     *
+     * @param callable $callback
+     * @return self
+     */
+    public function bootstrapping(callable $callback)
+    {
+        $this->listeners['bootstrapping'][] = $callback;
+
+        return $this;
+    }
+
+    /**
+     * Register a listener that will be executed after tenancy is bootstrapped.
+     *
+     * @param callable $callback
+     * @return self
+     */
+    public function bootstrapped(callable $callback)
+    {
+        $this->listeners['bootstrapped'][] = $callback;
+
+        return $this;
+    }
+
+    /**
+     * Register a listener that will be executed before tenancy is ended.
+     *
+     * @param callable $callback
+     * @return self
+     */
+    public function ending(callable $callback)
+    {
+        $this->listeners['ending'][] = $callback;
+
+        return $this;
+    }
+
+    /**
+     * Register a listener that will be executed after tenancy is ended.
+     *
+     * @param callable $callback
+     * @return self
+     */
+    public function ended(callable $callback)
+    {
+        $this->listeners['ended'][] = $callback;
+
+        return $this;
+    }
+}