feat: add attachment flags

[spifory]

Summary

• Implements Document attachment flags discord/discord-api-docs#6272

This is a Code Change

• I have tested my changes.
• I have updated the documentation to reflect the changes.
• I have run task pyright and fixed the relevant issues.

[spifory]

While the flags from discord/discord-api-docs#6272 (comment) need to be added too, I'd like for them to be in the actual documentation.

[ooliver1]

Draft as this is waiting on a docs PR.

[EmreTech]

Docs PR has been merged.

[ooliver1]

Tested

@bot.message_command()
async def flags(inter: Interaction, message: Message):
    await inter.send(
        ", ".join(f"{k}: {v}" for k, v in list(message.attachments[0].flags))
        if message.attachments
        else "no attachments"
    )