Random scenario selection options

Add two options in the World Defaults menu to enable random scenario selection for random characters.

Options:
- Random character and scenario  
- No challenges

This PR is a follow up to https://github.com/CleverRaven/Cataclysm-DDA/pull/9696.
"%s to reroll character, %s to reroll scenario and character"

Primary problem is that it's not clear just how much space we have available, especially at the default Really Cramped screen size.