x10k Management Core

Hello, Here we added a new main feature, that is PlaceholderAPI Support, because its the first time im working with it (as a big plugin with a lot of modules.), this will be an beta version, exepct some bug fixes, and more placehodler soon, meanwhile here are the new placeholders:

%xmc_rank% - Displays the highest rank name of the player
%xmc_rank_prefix% - Displays the formatted prefix of the player's highest rank (including colors and gradients)
%xmc_warnings% - Displays the total amount of active warnings the player has
%xmc_afk% - Displays "AFK" if the player is currently away from keyboard, otherwise empty