Attachment arguments in slash commands

[BeeFox-sys]

Description
This proposal suggests the ability to upload one, or potentially more, images as arguments for slash commands

Why This is Needed
Many bots take images and attachments as arguments in their commands, however slash commands cannot, meaning the user would have to link them. as a result many bots would not be able to change over to slash commands due to this

Alternatives Considered

alterntives are:

1. requesting an image posted after the slash command, this is an ok solution but defeats both the point of slash commands and the "ephemeral" idea of commands and responses, where on the user can see the command and response
2. not using slash commands, which is the current way bots are handling this

[advaith1]

#2322 (comment)

[sevenc-nanashi]

Implemented!