Added timeout and debugging statuses to webhooks

- Added a user-configurable timeout option to webhooks.
- Added webhook fields for last-call/error datetime, in addition to last
  error string, which are shown on  webhook edit view.

Related to #3122

database/migrations/2022_01_03_154041_add_webhooks_timeout_error_columns.php

@@ -0,0 +1,38 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+class AddWebhooksTimeoutErrorColumns extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up()
+    {
+        Schema::table('webhooks', function (Blueprint $table) {
+            $table->unsignedInteger('timeout')->default(3);
+            $table->text('last_error')->default('');
+            $table->timestamp('last_called_at')->nullable();
+            $table->timestamp('last_errored_at')->nullable();
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     *
+     * @return void
+     */
+    public function down()
+    {
+        Schema::table('webhooks', function (Blueprint $table) {
+            $table->dropColumn('timeout');
+            $table->dropColumn('last_error');
+            $table->dropColumn('last_called_at');
+            $table->dropColumn('last_errored_at');
+        });
+    }
+}