Wrong `height` value in Flutter's TextStyle

[ksokolovskyi]

According to the Flutter documentation of the TextStyle class (https://api.flutter.dev/flutter/painting/TextStyle/height.html): height - "The height of this text span, as a multiple of the font size."

Currently, when the user sets a Line height parameter of the font, the plugin just uses this value for the height of the TextStyle, which is wrong.

I propose to do the next:

1. Line height unit == AUTO: skip it in TextStyle;
2. Line height unit == PIXELS: set value as lineHeight.value / fontSize in TextStyle;
3. Line height unit == PERCENT: set value as lineHeight.value / 100 in TextStyle.