gh-138577: Fix keyboard shortcuts in getpass with echo_char (#141597)

When using getpass.getpass(echo_char='*'), keyboard shortcuts like
Ctrl+U (kill line), Ctrl+W (erase word), and Ctrl+V (literal next)
now work correctly by reading the terminal's control character
settings and processing them in non-canonical mode.

Co-authored-by: Victor Stinner <vstinner@python.org>
Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>