Support custom resolvedTheme

[phuctm97]

In multiple themes scenario with enableSystem=true, would be convenient to provide a custom them resolution logic. For example, one may have light, light-red, light-blue, dark, dark-red, dark-blue, a custom resolution will maintain same color, only change light ↔️ dark. This can currently be done by disabling enableSystem and implementing custom effect.

Suggested solution: allow optional prop resolveTheme, which is a function with argument is the current theme and resolved system theme.