Add some sort of handling for cache scenarios which'll lead to cases where entries are never uncached

[FasterSpeeding]

Summary

Add some sort of handling and documentation around cache scenarios which can lead to common cases where entries are never uncached.

Problem

If you don't have the guild or member intents declared then other cached guild bound entries won't be decached when the bot is removed from a guild.

This may include the following resources:

• Stickers (not implemented yet)
• Emojis
• Integrations (not implemented yet)
• Invites
• Voice States
• Presences
• Messages (i actually don't know if we clear these on guild delete right now)

Ideal implementation

This may be an error on init or a warning plus documentation around this behaviour.

Checklist

• I have searched the issue tracker and have made sure it's not a duplicate.
  If it is a follow up of another issue, I have specified it.

Other Information

This extends to threads which cannot be decached when the bot loses access to a guild or channel unless the following cache resources and their relevant intents are enabled:

• Channels
• Roles
• Guild
• Members (but only the current member matters so the intent isn't important)