[5.x] Add default config for select starter kit modules

[jesseleite]

This PR adds a default config, to help with module installation flow when spamming the enter key, or when running non-interactively. More specifically...

For standard confirmation-style modules (where user selects yes/no):

• default: true will ensure it gets installed when spamming enter or running non-interactively
• prompt: false will skip the confirmation prompt altogether, forcing the module to be installed
  • this is current behaviour, as documented here for organizational purposes

For select-style modules with options (where user selects A or B or C):

• default: antlers will ensure the antlers modules gets installed when spamming enter or running non-interactively
• skip_option: false will disable the option to skip the prompt altogether
  • if runing interactively, this forces the user to select an option
  • if running non-interactively, the default option will be installed

Examples...

modules:
  seo:
    default: true  # this still allows user to opt out, but defaults 'yes' when spamming enter or running non-interactively
    dependencies:
      - statamic/seo-pro
  js:
    default: mootools  # this will ensure the mootools module option gets installed if run non-interactively
    skip_option: false  # you can specify string for skip option label, or `false` to force user to select an option
    options:
      vue:
        label: 'VueJS'
        export_paths:
          - resources/js/vue.js
      react:
        label: 'ReactJS'
        export_paths:
          - resources/js/react.js
      mootools:
        label: 'MooTools (will never die!)'
        export_paths:
          - resources/js/mootools.js

TODO:

• Finish implementation
• Test coverage
• Docs PR Document new default and skip_option behavior docs#1558

[jasonvarga]

I tried this with a test starter kit and it seems that on a standard module step, default: true doesn't work. It still defaults to no.

The default value does seem to work on a multiple choice prompt, though.