feat: apply custom styling to active dropdown item

[SkMamtajuddin]

Description:
This PR introduces custom styling for active dropdown items in the RNPickerSelect component. It ensures that the active item in the dropdown menu is visually distinct by applying a specified custom style.

Changes Made:

1. Component Update:

   • Modified the RNPickerSelect component to accept and apply custom styles to the active dropdown item.
   • Integrated logic to apply the custom styles based on the current value of the picker.

2. Test Implementation:

   • Added unit tests to verify that the custom styles are correctly applied to the active dropdown item.
   • Ensured that the styles are applied when the picker value changes, and the active item reflects the custom styling.

3. Testing Enhancements:

   • Updated existing tests and added new ones to validate the custom styling feature.
   • Included both Enzyme and React Testing Library approaches to cover various scenarios and ensure robustness.

Additional Notes:

• The custom styles for the active item are defined through a customActiveItemStyle prop, which allows for flexible styling.
• The test cases have been adapted to verify the presence and correctness of the applied styles using different testing libraries.

Screenshots/GIFs:

Impact:

• This enhancement improves the visual feedback for users interacting with the dropdown, making it clear which item is currently selected.
• The added tests ensure that future changes to the component do not break the custom styling functionality.

Related Issues:

• Closes Need a styling for active or selected item #608

[SkMamtajuddin]

@remarkablemark can you please have a look on this ?

[codecov]

Codecov Report

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Additional details and impacted files

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