[6.x] Fix the actions dropdown separator and refresh listings after item actions

[duncanmcclean]

This pull request fixes a couple of issues with item actions in the dropdown at the top of the collection page:

• Fixes issue where a separator was shown in the dropdown even when the user wasn't authorized to run any actions.
  • This was happening because the separator was shown when there were config items or actions, rather than only when there were both.
  • I've fixed it by only showing the separator when there are items on both sides of it. This PR also applies the same fix to the asset container dropdown and the collections index.
• Fixes issue where the entries listing wasn't refreshed after running an action on a collection, even though actions can create or change entries.
  • This was happening because we only reloaded the Inertia props, which doesn't cause the listing to re-request its data.
  • I've fixed it by refreshing the current view (list, calendar or tree) once the reload completes. The tree is left alone when it has unsaved changes, matching how entry actions in the tree already behave.
  • This PR also refreshes the navigation tree after running an action on a nav, which had the same problem.

^ Not related to an issue. Just something I noticed on a personal site.