Allow modification of unselected checkbox color

[Silvyger]

Is your feature request related to a problem? Please describe. The de-selected item color in the modal defaults to a hardcoded 'white', this makes it difficult to create a dark mode variation of the modal.

https://github.com/azeezat/react-native-select/blob/b8fcaf0084ebacc2899cc3009009db726d172698/src/components/CheckBox/index.tsx#L27-L31

Describe the solution you'd like I want to be able to modify this value, or allow it to be transparent to match the background of the modal.

My workaround was to set this value to 'transparent' to display the way I intended.

Describe alternatives you've considered Add a new 'unselectedColor' similar to 'primaryColor' found in the Dropdown props OR add such option in the checkboxControls object like { checkboxUnselectedColor: ColorValue }