Add dialog dismiss listener

[Dhaval2404]

Add a helper method to allow the creator of a dialog to run some code when the dialog is dismissed.

• ColorPicker

    ColorPickerDialog
       .Builder(requireActivity())
       .setDismissListener {     // Proposed method
           // Handle Dismiss Event
       }
       .show()

• MaterialColorPicker

  MaterialColorPickerDialog
      .Builder(this)
      .setDismissListener {     // Proposed method
          // Handle Dismiss Event
      }
      .show()

Credit: @Surendar7 #12