Roadmap: setting parent channel improvements

[almostSouji]

Converting draft https://github.com/discordjs/discord.js/pull/4598 to an issue, since it serves the purpose of a note more than that of an actual draft at this point.

Setting the category of a guild channel is currently implemented with some major workaround. Should the suggested API feature come to pass this entire feature could very easily be implemented with a flag during the rest call.

Useful upstream topics:

• https://github.com/discord/discord-api-docs/discussions/3264
• https://github.com/discord/discord-api-docs/pull/1776