Adds String based inflections for Rust - feature "regex"

 Snake, kebab, camel, sentence, class, title and table cases as well as
 ordinalize, deordinalize, demodulize, foreign key, and pluralize/singularize
 are supported as both traits and pure functions acting on String types.
 .
 This metapackage enables feature "regex" for the Rust Inflector crate, by
 pulling in any additional dependencies needed by that feature.