fix - underlineColorAndroid not working on API 21

on API 21 we change the logic as follows to fix underlineColorAndroid:
- we store the bottomBorderColor in a local variable
- we set the bottomBorderColor to the same color of
  underlineColorAndroid
- we set the underlineColorAndroid
- we re-set the bottomBorderColor to the previous color

As by Facebook design it defaults to
transparent

facebook#18938
facebook#18988

but it is important to notice how this default is now not anymore used
as JAVA sets a new default of transparent for all colors (null is not
passed to this setter)

facebook#29412 (comment)

ReactAndroid/src/main/java/com/facebook/react/views/textinput/ReactTextInputManager.java

@@ -543,14 +543,17 @@ public void setUnderlineColor(ReactEditText view, @Nullable Integer underlineCol
       }
     }
 
-    if (Build.VERSION.SDK_INT == Build.VERSION_CODES.LOLLIPOP) { 
-      setBorderColor(view, 4, Color.TRANSPARENT);
-    }
-
     if (underlineColor == null) {
       drawableToMutate.clearColorFilter();
     } else {
-      drawableToMutate.setColorFilter(underlineColor, PorterDuff.Mode.SRC_IN);
+      if (Build.VERSION.SDK_INT == Build.VERSION_CODES.LOLLIPOP) {
+        int bottomBorderColor = view.getBorderColor(Spacing.BOTTOM);
+        setBorderColor(view, Spacing.BOTTOM, underlineColor);
+        drawableToMutate.setColorFilter(underlineColor, PorterDuff.Mode.SRC_IN);
+        setBorderColor(view, Spacing.BOTTOM, bottomBorderColor);
+      } else {
+        drawableToMutate.setColorFilter(underlineColor, PorterDuff.Mode.SRC_IN);
+      }
     }
   }