fix: ensure the correct window is activated on complete

When you complete a completion the completion window is no longer
activated after the callback is run. This was causing issues with the
incorrect window being active after the completion.

This will lead the way for more actions other then edit, that will be
comming soon.

Fixes-issue: #8

lua/ivy/controller.lua

@@ -37,7 +37,9 @@ controller.update = function(text)
 end
 
 controller.complete = function()
-  controller.checkpoint()
+  vim.api.nvim_set_current_win(window.origin)
+  controller.callback(window.get_current_selection())
+
   controller.destroy()
 end