Changes attribute names from enable_auto_*_contrast to force_*_contrast
to better match existing UI terminology and differentiate from single
theme contrast settings.
Replaces raw CSS selectors with reusable Capybara selectors following
the existing pattern used in primer_component_selectors.rb.
- Creates :theme selector for testing color modes and contrast settings
- Creates :auto_theme_config selector for auto theme configuration
- Updates interface tests to use new selectors with cleaner syntax
- Consolidates theme test helpers inline in interface_spec.rb
- Removes duplicate theme_matchers.rb file
* Use color, not colour for consistency
* Update spec/features/my/interface_spec.rb
Co-authored-by: Alexander Brandon Coles <a.coles@openproject.com>
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Co-authored-by: Alexander Brandon Coles <a.coles@openproject.com>
Kabiru Mwenja