Add players command to show online + offline players, alert when players connect + disconnected

[cavanpage]

I got inspiration and mirrored the logic from this other valheim repo which loops through log file to find online + offline players : https://github.com/cklokmose/vhstatus

core logic based off this: https://github.com/cklokmose/vhstatus/blob/2e505b75ebc2a72b8653e57711e9385454d36c96/index.js#L29

Features Added:

• ;players command to show online + offline players
• send notification when a user connects or disconnects from the server
• update regex to support more complex player names

Note - only supports 1 character per client since client ID is same for all users on a single machine/client