Add discord to players DB table

[Cocodrulo]

Description

Nowadays most servers using QBCore uses discord whitelist, so the player will have their discord linked to FiveM. To ease integration with webapges I think discord information in main qbcore database table (players) should be kept to easy locate characters linked to a player.

Checklist

• [x] I have personally loaded this code into an updated qbcore project and checked all of its functionality.
• [x] My code fits the style guidelines.
• [x] My PR fits the contribution guidelines.