Add the shortcut value on the different action tooltips

As of now, discoverability of shortcuts is relatively low.
When discussing an adjacent topic on the forum, this idea came up.
Adding the shortcut value to the tooltip of the action buttongs will help discoverability and make it easier for users to grow familiar with XWiki.

See https://forum.xwiki.org/t/adding-a-shortcut-for-the-create-action/14123/3 for more details and context.