By default the Chromedriver will send remote-debugging-port=0 to let the
browser choose a free port to listen on. The chosen port is written to
a known file in the user data dir that is passed to the app through the
CLI.
This PR does two things.
1. Correctly passes the USER_DATA_DIR to the remote debugging server so
it knows where to write the file
2. Adds support for --user-data-dir as we did not support that CLI
argument and Chromedriver relies on being able to tell the "browser"
where to write this file.
Fixes#17354
