Make Picker icon stylable and align it with visual style of modern iOS

[cpetrov]

Feature description

Currently, the "..." icon of the picker has a prominent blue color which is not customizable. Moreover, it does not match the visual style of modern iOS anymore.

Proposed solution

Make the color of the icon customizable to let it better integrate with various app color themes. Consider replacing it with an icon better suiting modern iOS, e.g. ">":

Original screenshot	Annotated screenshot

Source: https://developer.apple.com/design/human-interface-guidelines/ios/controls/pickers#date-pickers