feat: add send_voice_messages permission

[onerandomusername]

Summary

Adds the new permission for sending voice messages.

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, ...)

[shiftinv]

This should be combined with the other voice message related changes, and have one changelog entry for the permission bit + other fields.
I've pushed the other things here, would be great if you could pull them into this PR.

[onerandomusername]

This should be combined with the other voice message related changes, and have one changelog entry for the permission bit + other fields. I've pushed the other things here, would be great if you could pull them into this PR.

I'd rather get the permission in now, as that doesn't require much of a review.

[shiftinv]

I'd rather get the permission in now, as that doesn't require much of a review.

Fine, I suppose.

[shiftinv]

Not having send_messages permissions should implicitly deny send_voice_messages:

[onerandomusername]

Not having send_messages permissions should implicitly deny send_voice_messages:

Fair, I forgot about this because that is part of the code is completely wrong.

[shiftinv]

lgtm, ty