[API] Do not send AFK message by default whenever NucleusAFKService#setAFK is used

[02Miki]

What are you trying to do?
I'm creating a plugin that sets people to afk if they stand on a specific block, and even if I do have a cooldown set, it can get spammy sometimes

Describe the solution you'd like
I'd say don't send the message by default, and send it only if a boolean is set to true in the method?
Describe alternatives you've considered
Or have a method in the API that allows devs to retrieve the AFK message format from the config, so they can print the message manually

Anything else that might help?
Not really