Implement a non-Core FFXIV Alerts & Events plugin for FFXIV-exclusive alerts/reminders + event management

[MKhayle]

Describe the solution you'd like
(Thanks @ArcaneDisgea for suggesting it in #3)
This plugin should interface with #72 and use methods to set FFXIV-exclusive alerts and reminders, as events starting/finishing (soon), daily / weekly duties, and potentially merge #71 in it for Fashion Report. In regard to this plugin's handling of in-game events of various kinds and interacting with alerts, it sounds good to me that we also make it manage events too. If possible, we should use the existing Discord Event system?

• Display data about ongoing FFXIV Events
• Set/Unset alerts for specific daily/weekly duties
  • Daily reset for roulettes
  • Daily reset for GC Supply/Provisions
  • Weekly reset for Khloe's
  • Weekly reset for Custom Deliveries
  • Weekly reset for BLU missions in general
  • Weekly starting time and ending time for Fashion Report
• Manage FFXIV events
  • Create Event templates (for recurrent event types)
  • Create polls to check people's availability before creating an actual event
  • Allow setting up different role slots (especially for raiding content)
  • Create events of various types (RP, FC gathering, Raiding content, etc)
  • Send a reminder to participants (via direct message or pings?)

Additional context
See this for the Discord built-in event system documentation.