Add Max Concurrent Connections for database users

Closes #1849

Allows database users to be limited to a number of concurrent connections to prevent one user from connecting hundreds of time and bottlenecking the MySQL server.

database/migrations/2020_04_22_055500_add_max_connections_column.php

@@ -0,0 +1,32 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+class AddMaxConnectionsColumnToDatabasesTable extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up()
+    {
+        Schema::table('databases', function (Blueprint $table) {
+            $table->integer('max_connections')->nullable(false)->default(0)->after('password');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     *
+     * @return void
+     */
+    public function down()
+    {
+        Schema::table('databases', function (Blueprint $table) {
+            $table->dropColumn('max_connections');
+        });
+    }
+}