Move HAML linter InlineJavaScript into haml_lint/linter

What does this MR do and why?

This MR simplifies the setup for linter InlineJavaScript:

• Removes custom require in rake task
• Removes requires and production? guard in linter
• Adds require to .haml-lint.yml as suggested in HAML linter docs
• Adds missing specs

This MR also improves spec runtime of HAML linter specs by using fast_spec_helper.

Screenshots or screen recordings

n/a

How to set up and validate locally

bundle exec rake haml_lint

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.