Allow channel parameter in bot scope

[muddyfish]

Description

Complementing #2216, it would be great if the channel_id parameter already possible for webhook.incoming was available for the bot scope. If given in combination with the guild_id parameter, it would create a user level override granting the permissions you have selected. This of course would only be available when the bot is already in the guild (I guess this is optional, but would be a little weird otherwise.)

Why This is Needed

This would provide a simple interface which allows users to fix permissions issues by clicking a link rather than needing to understand the permissions structure, and would improve the user experience. Often I find that users get confused if they've set up some permissions override for a channel for some role the bot has, but aren't intended it to affect the bot itself and declare it broken. The current experience is pretty hard for people to know why something is broken, and bots can only do so much to signpost they need additional permissions to function in the current channel.

Alternatives Considered

Allow bots to bring up an interface with a pre-filled modification in the client to change permissions in some way.

Additional Details

In an ideal world, you would be able to also supply a role id to grant the permission to.

In particular, I want my bot to be able to allow people to easily give the @everyone role the 'use external emojis' permission in a channel, which isn't easy to signpost it needs to be that particular override as it's not directly modifying the bot's permissions.

[advaith1]

Allow bots to bring up an interface with a pre-filled modification in the client to change permissions in some way.

#1657 (comment)