Add /help command and various gameplay fixes

Introduce a HelpCommand (/help) and register it in SpeedHG; add its localized help text and plugin.yml entry. Prevent kit ability use while in gladiator by checking metadata in KitEventDispatcher and add a matching translation key. Early-return in KitCommand during ENDING state. Fix English message in TeamCommand and adjust spacing in LeaderboardMenu lore. Remove an unused import in SpeedHG and add necessary imports.

src/main/resources/plugin.yml

@@ -23,6 +23,8 @@ permissions:
     default: false
 
 commands:
+  help:
+    description: 'Help Command'
   kit:
     description: 'Select kits via command'
     usage: '/kit <kitName> <playstyle>'