Added perron binstub/exe

[eelcoj]

Adds a perron exe/binstub:

perron -h
Unknown command: -h
Usage: perron <command> [options]

Commands:
  perron new APPNAME    Create a new Perron-powered Rails app
  perron generate NAME  Scaffold a new content type (actions: index show)
  perron validate       Validate all content resources
  perron sync_sources   Sync all source-backed resources (pass NAME to sync specific)
  perron build          Build static site (defaults to RAILS_ENV=production)
  perron clobber        Remove built output
  perron deploy         Deploy static site

Examples:
  perron new my-site
  perron generate Post show index
  perron destroy Post
  perron sync_sources Tool

perron new my-site, when perron is installed globally (gem install perron), replaces the library snippet (rails new my-new-site --minimal -T -O -m https://perron.railsdesigner.com/library/new/template.rb).

perron build (and sub-sequentially perron deploy), allows to set RAILS_ENV=production), thus cleaner than the current RAILS_ENV=production bin/rails perron:build.

Most are "thin wrappers" for current bin/rails perron:* tasks.

One thing I would like to add is perron content CollectionName (same as current bin/rails content *). Left it out as I have some ideas I want to explore to extend it with.

/ht @ianyamey for the idea 💡