Re-introduce Text() on TextParser<char[]> and TextParser<TextSpan>

[ewoutkramer]

Sprache had a Text() combinator that was basically a shorthand for .Select(cs=>new string(cs)) on a Parser<char[]>.

Would it be useful to re-introduce this in Superpower, also using it on TextParser<TextSpan>? (basically equivalent to .Select(sp => sp.ToString())?