feat: add new poll system message type

[Snipy7374]

Summary

• Closes implement new poll system message type #1212

This is something new for me so i want to ask if i need to add the new fields documented in the discord PR respectively to the Embed and Message class

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 pdm lint
  • I have type-checked the code by running pdm 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, ...)

[Snipy7374]

The "s: waiting for api/docs" label can now be removed 🙏🏻

[shiftinv]

edit: disregard this comment

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Seeing how the poll result embeds are currently structured, I don't think we can represent them entirely in system_message - the result (with a clear winner) looks like this, for instance:

The closest would be something like the following, which doesn't really make sense on its own:

{author}'s poll {question} has closed.

{answer_text}
Winning answer • {maths}%

Just having the first line would be enough, in my opinion.