This PR modernizes the taxon menu, bringing it up to the same standards and look-and-feel as our model ,life and ,taxon list commands. All menu, source, and formatter concerns are split off and moved down to dronefly-discord and dronefly-core as needed. When complete, it will finally resolve #141 .

Concepts

• Social buttons are buttons that any registered user can use to update the menu. For example, the 👤 button is a social button to add or remove the user's own stats for the current display.

Tasks

• Convert reaction menu to component-based menu.
• Eliminate round-trip to read/write the message each time a user presses a social button.
• Use taxon count list source to handle user and place stats tables.
• Use taxon count formatters for user and place entries.
• Replace predicate-based user and place query with modal dialogs to handle adding arbitrary user or place (i.e. user 👥 and place 🌍 social buttons) privately.
• Make interactions cache persist across cog reloads.
• Remove buttons and expire associated interaction cache when the menu messages are no longer in the Discord cache (avoids exceeding DIscord's rate limit on editing old uncached messages).