feat(channel): support spoiler channels

[shiftinv]

Summary

discord/discord-api-docs@fa2cdf8

This adds ChannelFlags.spoiler, and adds a flags parameter to the Guild.create_*_channel() and *Channel.clone() methods.

It's worth noting that the API docs explicitly specify that this flag is not supported in stage channels, despite it being implemented that way in the client, as well as being accepted just fine by the API. I've added the flags parameter to stage channel creation anyway, if Discord changes their mind and enforces this limitation for some reason, it'll only be a documentation change.

Setting flags on thread creation unfortunately does not appear to be supported, only on thread edit.

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 uv run nox -s lint
  • I have type-checked the code by running uv run nox -s 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, ...)

[read-the-docs-community]

Documentation build overview

📚 disnake | 🛠️ Build #34435968 | 📁 Comparing 53c01c9 against latest (95f5d6a)

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51 files changed · ± 51 modified

± Modified

• genindex.html
• index.html
• intents.html
• whats_new.html
• api/abc.html
• api/activities.html
• api/app_commands.html
• api/app_info.html
• api/audit_logs.html
• api/automod.html
• and 41 more...