Update subprocess.Popen documentation wrt universal_newlines arg (GH-10337)

Update subprocess.Popen documentation wrt universal_newlines arg (GH-10337)

* universal_newlines defaulting to False would suggest, that not
  specifying universal_newlines explicitly and setting text to True
  should cause an error, which is not the case.
* The run function didn't have the universal_newlines parameter
  documented
* The check_output function didn't have its text parameter documented
(cherry picked from commit 7432f0929f2e90bde30e089da8e1efc580ccade1)

Co-authored-by: Jakub Stasiak <jakub@stasiak.at>