Refactor global DEBUG_ENABLED to module-based configuration

[ny1020]

Description

This PR refactors the handling of the DEBUG_ENABLED flag in the RSpec::OpenAPI project. Previously managed as a global variable, this refactor introduces a more encapsulated and controlled approach.

Motivation

The motivation behind this change is to improve code quality by increasing modularity and reducing global state.

Changes

1. Introduction of Config Class: Created a Config class within the RSpec::OpenAPI module to manage configuration settings, including the DEBUG_ENABLED flag.

2. Module-based Configuration Access: Shifted the access of the debug configuration to be through RSpec::OpenAPI::Config.debug_enabled, making its use more explicit and restricted to the module's context.

3. Environment Settings Loader: Added load_environment_settings method to the Config class to initialize configuration based on environment variables. This method is called conditionally when the OPENAPI environment variable is set.

[codecov]

Codecov Report

Attention: Patch coverage is 81.25000% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 97.14%. Comparing base (4e3b8d2) to head (dfad466).

Files	Patch %	Lines
lib/rspec/openapi.rb	81.25%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #220      +/-   ##
==========================================
+ Coverage   97.12%   97.14%   +0.02%     
==========================================
  Files          20       20              
  Lines         626      631       +5     
  Branches      143      144       +1     
==========================================
+ Hits          608      613       +5     
  Misses         18       18              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[exoego]

Thanks.
Confirmed it works for Rails when Hanami not bundled.