Implement slash (/) commands to replace "!" command syntax

[GumptionWare]

This will be an "Admin" function because we will only execute this logic when linking KnowBot to a new guild.

Logic Outline

1. Figure out if our commands are already present:

IEX> Nostrum.Api.get_global_application_commands (Global commands)

IEX> Nostrum.Api.get_guildl_application_commands(<guild_id>) (Guild level commands)

2. If NOT already present, execute create_command logic:

• Nostrum.Api.create_guild_application_command(guild_id, command)
  ... where command is structured like here: (https://kraigie.github.io/nostrum/application-commands.html#getting-started)

NOTE: We show the create_guild_application_command syntax instead of the create_global_application_command syntax, which may not be the best practice once the initial development is completed.

• The create_guild... syntax is intended for quick feedback during development and debugging.
• Using the create_global... syntax is probably better as the "go-to" in the published admin functionality.

3. Confirm the list of commands by repeating the applicable flavor of step 1 above.

To-Do (maybe sub-tickets)

• /Help (... /h, /help, /?)
• /FAQ
• /Q ( ... /q, /question ... /ask /ASK ...)
• /Answer
• Expose a button in Discord .... click the button to answer that question.