Core/Vehicles: add a way to delay the Vehicle despawn Time if its needed.

Port From (https://github.com/TrinityCore/TrinityCore/commit/c7b10d3c5fd082faf6c2835239e340babc3dfc76)

sql/updates/world/master/2020_12_31_00_world.sql

@@ -0,0 +1,15 @@
+--
+-- Table structure for table `vehicle_template`
+--
+DROP TABLE IF EXISTS `vehicle_template`;
+CREATE TABLE `vehicle_template` (
+  `creatureId` int(10) unsigned NOT NULL,
+  `despawnDelayMs` int(11) NOT NULL DEFAULT '0',
+  PRIMARY KEY (`creatureId`)
+) ENGINE=MyISAM;
+
+DELETE FROM `command` WHERE `name`='reload vehicle_template';
+INSERT INTO `command` (`name`,`permission`,`help`) VALUES
+('reload vehicle_template', 881, "Syntax: .reload vehicle_template
+
+Reloads vehicle template definitions from the database.");