Restore user ability to toggle ivy related hydras

There are two hydras that can be opened from ivy interface:

1. `ivy-dispatching-done' (doom key: "C-o", vanilla key: "M-o")
2. `hydra-ivy/body'       (doom key: "M-o", vanilla key: "C-o")

Original behavior is that they both can be exited / toggled
by the same key they were opened.

This commit restores the original behaviour but does it without
reverting the decision to swap the "C-o" and "M-o" key bindings.

modules/completion/ivy/config.el

@@ -96,6 +96,12 @@ results buffer.")
   (after! yasnippet
     (add-hook 'yas-prompt-functions #'+ivy-yas-prompt-fn))
 
+  (after! ivy-hydra
+    ;; Ensure `ivy-dispatching-done' and `hydra-ivy/body' hydras can be
+    ;; exited / toggled by the same key binding they were opened
+    (add-to-list 'ivy-dispatching-done-hydra-exit-keys '("C-o" nil))
+    (defhydra+ hydra-ivy () ("M-o" nil)))
+
   (define-key! ivy-minibuffer-map
     [remap doom/delete-backward-word] #'ivy-backward-kill-word
     "C-c C-e" #'+ivy/woccur