Add existing ruby-ruby_parser package
Update ruby-ruby_parser to version 3.2.2

Also:

* Properly quote and escape several variables.
* Add a sha256sums array.
* Remove ruby from the "depends" array. ruby-sexp_processor already depends upon
  ruby, so requiring ruby here is redundant.
* Add a license file and install it with the rest of the package. This is
  necessary because the license is MIT, and each MIT-licensed package must have
  a unique copy of that license. (technically)
* Make _gemdir a readonly variable.
* Add self as a contributor.