Remove "stack ide" command

[mgsloan]

Since we're no longer working on / maintaining https://github.com/commercialhaskell/stack-ide , it makes sense to remove it from stack.

[mgsloan]

Done

[chrisdone]

stack ide targets which is used by intero for target completion is still there though right?

[borsboom]

@chrisdone: Looks like it's still there.