feat!: provide guild objects in interactions when guild is uncached

[onerandomusername]

Summary

Checklist

• If code changes were made, then they have been tested
  • I have updated the documentation to reflect the changes
  • I have formatted the code properly by running task lint
  • I have type-checked the code by running task pyright
• This PR fixes an issue
• This PR adds something new (e.g. new method or parameters)
• This PR is a breaking change (e.g. methods or parameters removed/renamed)
• This PR is not a code change (e.g. documentation, README, ...)

[shiftinv]

If this is changed now, we should look at other occurences of _get_guild where a guild may not be cached (like invites), and change them accordingly as well.

With the changes in this PR, this part could be simplified too:

disnake/disnake/interactions/application_command.py

Lines 396 to 402 in 076adda

	guild: Optional[Guild] = None
	# `guild_fallback` is only used in guild contexts, so this `MISSING` value should never be used.
	# We need to define it anyway to satisfy the typechecker.
	guild_fallback: Union[Guild, Object] = MISSING
	if guild_id is not None:
	guild = state._get_guild(guild_id)
	guild_fallback = guild or Object(id=guild_id)

[onerandomusername]

I think this might be fine how it is (for now) since it somewhat moves the exceptions to a different point. OTOH repr for a thread will no longer crash in this case.

[shiftinv]

Closing this for now, since the API provides a (very) partial guild object as of a few weeks ago, which we should implement instead.