Re-export StdStream from process

[koterpillar]

I'd like to only depend on process-extras but still be able to say (example from process):

createProcess (proc "ls" []){ std_out = CreatePipe }

Currently System.Process.ListLike reexports proc and CreateProcess(..) (so std_out is in scope) from process but not StdStream so I cannot use its constructor CreatePipe.

[koterpillar]

On further inspection, standard streams are always forced to be CreatePipe by this package which is a separate issue but makes the potential re-export useless.