Explore parsing Ruby package files without running them

[apainintheneck]

This is essentially an extension of some of the talk that's happened in the main Brew repo over the last few months.

Things to keep in mind:

• This is often slower than just evaluating the Ruby scripts
• Are there things we can ignore when parsing
• The parser gem seems to be too slow for this use case
• The ripper gem is faster but is essentially legacy code at this point
• The new prism gem is interesting but will have to wait until we get on Ruby 3.3
  • Note: We're currently on Ruby 3.1 as of 2024-01-25
• In all likelihood, this won't be something that will make it into the main Brew repo
  • Too slow to be worth the effort
  • Won't likely scale well to 6k formula and 4k casks