Feature Request: Custom navigation header shadow colour support for theme customisation

[stage88]

Hello react-native-screens maintainers and community,

I've been using react-native-screens for a while now and it's been instrumental in building navigation in my React Native applications.

I'm reaching out to request a feature that I believe could benefit a number of us in the community: the ability to customise the navigation header shadow color dynamically. This would allow for a seamless transition between themes and ensure that the shadow under the navigation header can be tailored to match the selected theme, whether light, dark, or custom.

It would be great if react-native-screens could expose a simple prop for the Screen component, something like shadowColor, which we could then dynamically set based on the active app theme.

Thank you for your time and consideration!