Allow for (unpinned) ByteArray# to be written directly to a Handle

Motivation

From what I understand, currently writing an (unpinned!!) Text or ShortByteString value to a Handle always requires reallocation of the underlying payload.

My understanding is that there is currently no way to work around this as GHC.IO.Device.RawIO puts hard limits on what you can do with a handle.

Proposal

Add four new methods to RawIO that work with ByteArray instead of Ptr Word8:

• readByteArray :: a -> MutableByteArray s -> Word64 -> Int -> IO Int
• readNonBlockingByteArray :: a -> MutableByteArray s -> Word64 -> Int -> IO (Maybe Int)
• writeByteArray :: a -> ByteArray -> Word64 -> Int -> IO ()
• writeNonBlockingByteArray :: a -> ByteArray -> Word64 -> Int -> IO Int