ChannelGuildCategory missing some major fields

[yutotakano]

The fields available in the current ChannelGuildCategory ADT are quite limited currently, as seen here: https://github.com/aquarial/discord-haskell/blob/ffe46538c508f498b7cd98367c2aec16ede7e8e7/src/Discord/Internal/Types/Channel.hs#L117-L120

This raises some inconsistencies, as R.ModifyChannel can modify positions and permission overwrites of both channels and categories, while it is only possible to retrieve them for normal channels through R.GetChannel.

Discord's blog post on categories highlights that categories can have permission overwrites and positions. More concretely, the rightmost column in the table in the relevant docs show that all types of channels have permission_overwrites and position. Although this seems misleading since DM channels for one don't have those, I think we can be sure that category channels would have those fields.

Could these be implemented?

[aquarial]

Yeah this is a good idea. I can work on it

[aquarial]

Updated 1.8.6 with this change

Thanks for providing detailed report!