Create broadcast function

[Dashboy1998]

Context

• Added broadcast function and check if message is ASCII as mentioned in Create broadcast function #400
• Code from Move countdown to function for auto update and auto reboot #392

Choices

• Added in checking for ASCII so users trying to use none ASCII. Staging for Implement CLI for RCON commands #401 and to give users more insignt for issues like rcon-cli does not support utf-8 messages #253

Test instructions

1. Test the broadcast in game by scheduling a cron reboot
2. Verify the message as underscores in game

Checklist before requesting a review

• I have performed a self-review of my code
• I've added documentation about this change to the README.
• I've not introduced breaking changes.