Updated slash command

[dustinnewbold]

Added new feature support to extend usability of slash commands with the following purpose:

1. To output messages to allow a user to know the changes going on within the Addon. This includes supporting "help" messaging when a command is invalid.
2. Supporting additional methods to adjust configuration, including toggling between enable/disable and putting the "element" first. For example, the current live version of this addon would only support /bif enable color or /bif disable color. With this change, a user could use the two commands above. However, a user could also use /bif color enable, /bif color disable, or even /bif color to toggle between the enable/disable for that configuration item.

Changelog

Refactored slash command function to support the following items:
- Displaying help text when no command or invalid command is provided
- Supporting enable/disable as first or second argument
- Supporting toggling of a configuration item
- Outputting messages for updates to any configuration change