Feature: Push-buttons on storybook pages (#7896)

Allow more direct player-initiated interaction for Game Scripts, by letting the GS put push-buttons on storybook pages. These buttons can either trigger an immediate event, or require the player to first select a tile on the map, or a vehicle.

Additionally this reworks how the storybook pages are layouted and rendered, to allow for slightly more complex layouts, and maybe speeding drawing up a bit.