[FEATURE] Standup Plugin improvements

[en3sis]

📝 Is your feature request related to a problem? Please describe.

I'm currently implementing a new plugin for Standups with limited functionality (Monday - Friday at a given hour, single channel)
This Issue is to have a follow-up and improve it.

🧬 Describe the solution you'd like

• Allow creating multiple standups per guild (metadata[{standups}])
• Command that shows all standups and an option to stop/remove a given standup.
• Move everything to it's command (/standup)? This might require thinking, maybe we can rework the plugins/commands functionality.

👩🏼‍💻 Additional context