Roadmap: setting parent channel improvements

[almostSouji]

Converting draft #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:

• Request: Add lock_permissions to PATCH/channels/{channel.id} discord/discord-api-docs#3264
• chore: document missing properties in Modify Channel Positions endpoint discord/discord-api-docs#1776