Allow fitting text instead of ellipsis

[LuisMiguelSS]

If the text (String label) of an SlidableAction is bigger that what can be fit, the ellipsis is shown, as directed in

      children.add(
        Text(
          label!,
          overflow: TextOverflow.ellipsis,
        ),
      );

It would be nice to allow making the text shrink as needed, probably by adding a FittedBox as asked in this StackOverflow question.

I can upload a pull request if needed.

[LuisMiguelSS]

Please note that this could also be done via a CustomSlidableAction with a custom Widget, but may still be a nice add-in.

[letsar]

There is a ton of specialized feature request concerning SlidableAction. I prefer to redirect towards CustomSlidableAction in these case otherwise SlidableAction would become too complicated.