interactivity service

[BIRD311]

adds textinput popus to custom command "as custom", add and edit

That's basically what I have shown on discord. Try it tell me what you think. Here are some things I wanted to mention:

• Edit only shows the popup when you edit the description because everything else is short and the textinput thing isn't perfect
• I can add more fields for add and "as custom" if you want I just left it simple for now
• I didn't see any response if a popup was closed so this will hit the timeout
• I didn't find a way to change "something went wrong" error so this either means the command exists or the timeout was reached
• I can send a channel message if there is a timeout but not respond to something so the message can't be ephemeral (I think)

[tsa96]

Needs a rebase please! Some conflicts in the slash command service