Adjust row height by font size in PickerIOS

There is a problem where setting a bigger fontSize in PickerItem style
clips the top and bottom of the text.
This solves that problem by computing the row height using the font
size.

Author: alin23

React/Views/RCTPicker.m

@@ -70,6 +70,10 @@ - (NSString *)pickerView:(__unused UIPickerView *)pickerView
   return [RCTConvert NSString:_items[row][@"label"]];
 }
 
+- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component {
+  return _font.pointSize + 19;
+}
+
 - (UIView *)pickerView:(UIPickerView *)pickerView
             viewForRow:(NSInteger)row
           forComponent:(NSInteger)component