Improve action list add action UX

[jrmi]

in the left pane, the "Add an action ..." combobox is found below the list of actions. Problem: when you add an action, the combobox is pushed downwards, which means you have to scroll to see it.

• Solution 1: place the combobox at the top of the list of actions. This way, we can add new action quickly without having to scroll.
• Solution 2: leave the combobox at the bottom. This makes it possible to force the user to always have a visual on all the added actions.