add pretty tabComplete

[Soul-KRT]

Changes Made

• add CommandManager to PartyCommand constructor
• add some methods in CommandManager
• add pretty tabComplete to all commands

Reason for Changes

• tabComplete was so ugly and don't work

[Dominik48N]

Thank you for the contribution!
There are many changes in the pull request that do not belong to the Complete tab.
The multi-proxy support would also no longer be 100% guaranteed with this tab-complete. Only the player names of the players on the same proxy server are suggested.

However, the tab complete would take too long with larger numbers of players to extract and filter all players from Redis.
I think such a tab complete for all players in the network would also be disadvantageous for vanish players on some servers, which is why if you were to add something like this, an option in the config would be appropriate.

Thanks for the contribution anyway, but I'll close the pull request.