Add a function to split text at the first occurrence of a character

[vsannier]

I was surprised not to find a function in the library to split a text on the first match of a character/text/predicate, with the matched part discarded.
This is not difficult to write using breakOn and drop, but I think a function implemented with the internals of the library might have better performance.

split1 :: Char -> Text -> (Text, Text)
split1 c = (id *** drop 1) . (breakOn $ singleton c)

See a similar function (previously called splitOnce) in the byteslice package, and a question on Stack Overflow about splitAtfirst.

[Bodigrim]

IMHO split1 c = fmap (drop 1) . break (== c) is short enough and does not suffer from any significant performance penalty: drop 1 is constant-time, negligible in comparison to the linear time of break.

Note that the function from byteslice has a different signature, with Maybe.