Clean up deprecated code and simplify validations

This PR removes deprecated code and simplifies the validation system in Grape.

Changes

Removed Deprecated Methods

• rack_response method: Removed from Grape::DSL::InsideRoute module
  • This method was deprecated in favor of using error! instead
  • Removed associated deprecation warning and tests

Removed Deprecated Exception Aliases

• Grape::Exceptions::MissingGroupTypeError: Removed deprecated alias for MissingGroupType
• Grape::Exceptions::UnsupportedGroupTypeError: Removed deprecated alias for UnsupportedGroupType
• Updated specs to remove references to these deprecated classes

Removed Deprecated Base Class

• Grape::Validations::Base: Removed deprecated base class
  • Users should use Grape::Validations::Validators::Base instead
  • Removed associated deprecation warning

Simplified Validation Logic

• params_scope.rb: Simplified validation parameter handling
  • Removed deprecated excepts parameter from validation methods
  • Consolidated except_values handling logic
  • Cleaned up method signatures and reduced code complexity

Test Cleanup

• deprecated_class_examples.rb: Removed shared spec file for deprecated classes
• Updated all specs to remove references to deprecated classes and methods
• Removed deprecation-related test cases

Impact

Breaking Changes

• rack_response method: No longer available, use error! instead
• Exception aliases: MissingGroupTypeError and UnsupportedGroupTypeError removed
• Base class: Grape::Validations::Base removed

Code Quality Improvements

• Reduced codebase complexity by removing deprecated code paths
• Simplified validation parameter handling
• Cleaner exception hierarchy
• Reduced maintenance burden

Migration Guide

For Users of rack_response

Replace:

rack_response('message', 500, headers)

With:

error!('message', 500, headers)

For Users of Deprecated Exception Classes

Replace:

Grape::Exceptions::MissingGroupTypeError
Grape::Exceptions::UnsupportedGroupTypeError

With:

Grape::Exceptions::MissingGroupType
Grape::Exceptions::UnsupportedGroupType

For Custom Validators

Replace:

class MyValidator < Grape::Validations::Base

With:

class MyValidator < Grape::Validations::Validators::Base

Testing

• All existing tests pass
• Removed deprecated code paths and associated tests
• No new functionality added, only cleanup

Related Issues

This cleanup addresses technical debt and removes deprecated code that was marked for removal in previous versions.