Use TapActionCell's tintColor as its label textColor

[sanekgusev]

This PR attempts to fix a pretty minor issue of TapActionCell's textLabel not following the modified tintColor when setting a custom tintColor on the application's main UIWindow instance (which is a somewhat common approach to theming the entire app).

Since currently the text color is derived from a temporarily created button which is never inserted into the view hierarchy, it stays equal to the default system tint color, not the (potentially) overridden one.

After this change, the label's text color will follow its TapActionCell's tintColor which sounds like intended and reasonable behavior to me.

The downside is that overriding this text color via UIAppearance will now need to be done by manipulating TapActionCell's tintColor property though the cell's appearance proxy, and not directly through UILabel's proxy (since UIAppearance will notice the property having already been modified by the cell and will not proceed with update).

[bcylin]

This is way better than the temporary button. Thank you very much 👍