Refactor command handler and error handling

[outmaneuver]

Move command handler to utils and add error handling decorator.

• Command Handler:

  • Add utils/command_handler.py to handle commands.
  • Move command handler logic from selfbot.py to utils/command_handler.py.
  • Define CommandHandler class to handle commands and interactions.

• Error Handling:

  • Add utils/error_handler.py to handle errors.
  • Define error_handler decorator to handle errors.
  • Refactor existing error handling logic into the decorator.

• SelfBot:

  • Remove command handler logic and import from utils/command_handler.py.
  • Remove error handling logic and import from utils/error_handler.py.
  • Update SelfBot class to use CommandHandler and error_handler.

• Cogs:

  • Remove try-except blocks and use error_handler decorator in cogs/custom_activity_cog.py, cogs/help_cog.py, cogs/moderation_cog.py, cogs/name_history_cog.py, and cogs/avatar_history_cog.py.
  • Import error_handler from utils/error_handler.py in each cog file.
  • Apply error_handler decorator to command methods in each cog file.