Halt/init a collection of keys

[nivekuil]

Integrant itself can take a collection of keys for init and halt to selectively act on keys but the required arity is not taken by integrant-repl. I occasionally find myself reaching for this since I have one key that is somewhat expensive to restart, so I just have my halt function go through integrant directly. Would it make sense to expose this functionality in integrant-repl as well?