Update Art Book Next to latest version

This PR contains a full refactor to bring Art Book Next up to date with the latest theme engine features available in Batocera v39 and later. As such the changes in this version will not work in versions of Batocera below v39. If you would like to use Art Book Next in an older version of Batocera then you can download the source at this commit

Changes:

Added an additional set of System Artwork called Noir that was created by tenlevels with help from f8less and inspired by the artwork from the Epic Noir theme by chicuelo.
Added a built-in Font Size option to enable you to change the size of text elements throughout the theme. Contains 3 options: Default, Small and `Large.
Updated the customization options to focus only on system artwork and color schemes. Note: the folder for custom artwork changes from backgrounds to artwork to better align naming.
Updated the built-in color schemes to fully match the set I've made for the ES-DE version of this theme.
Added the help system for all aspect ratios. Help System can be turned off by going to Main Menu > User Interface Settings > On-Screen Help
Added an option to select the Game Artwork that displays on the gamelist. The options are aligned with the settings that can be made in Main Menu > Scraper > Scraper Settings. Please see this section of the readme for details on my recommended settings.
Added an option to turn the display of game metadata on/off when viewing the gamelist
Added the option to turn the display of system clock on/off.
Added Knulli to the list of Distributions (this is used to set the location for user customization)