Slash Commands Emoji input type

[Skye-31]

Description
This feature should allow users to enter emojis, like the roles & channels, etc types.

Why This is Needed
This allows users to specify emojis, both custom and default, to be used in interactions. The only current way is using a string argument, and validating it. While this is easy enough for custom emojis, it's trickier for default ones. Other issues in this repo have presented how discord uses a modified version of twemoji 12 (edit: now 13), and the mobile clients also send some emojis in a different format to desktop. This makes it significantly harder to validate these arguments.

Alternatives Considered
N/A

Additional Details
N/A

[garantiertnicht]

My use case for this would be manipulating emojis on a guild. I would therefore like to be able to restrict it to custom emojis from that guild.

[HonzaKubita]

This would make implementing something like reaction roles so much easier

[JDJGInc]

This would make my emoji info command so much easier to do and it would also other uses.

[JDJGInc]

this would be for making roles via default slash command, and plus making it a lot easier for bot developers to parse default emoji and partial emoji.