v0.1.5: add help command and improve CLI UX

• Add HelpProvider class for help text display
• Add /yeetables help subcommand
• Show help when running /yeetables with no arguments
• Check give permission before requiring player context
• Add help to tab completion
• Fix Makefile to create bin directory before copying
• Add clean target to remove bin directory
• Update server jar to paper-1.21.11-55
• Increase slime_ball bounce count from 3 to 5