Fixed #19508 -- Used uri_to_iri.

This is a PR for ticket #19508 for which another PR #2919 was opened by me a few days ago.
This PR implements `uri_to_iri` as per RFC and changes the `PATH_INFO` at the very time when `environ` is being set contrary to the previous one which corrected the received url from `environ`.
`environ[PATH_INFO]` is set through this function....and as far as I have seen `environ` values are bytes..
See function: `get_bytes_from_wsgi` and `get_bytes_from_str`.