Add -no-progress and --json options to mix:compile and mix:list respectively

[Nimdoc]

• Add --no-progress option to mix:compile

This will suppress the mix progress output while allowing the webpack progress to be output.

• Add --json to mix:list

This outputs the mix package information in a json format. Also instead of "yes" and "no" for the "active" property, with the --json option the values are true and false.

These additions will be useful for scripts or automation tools that need to parse information about mix packages and information for when they're compiled.