[3.12] gh-110392: Fix tty functions (GH-110642) (GH-110853)

* tty.setraw() and tty.setcbreak() previously returned partially modified
  list of the original tty attributes. Now they return the correct list of
  the original tty attributes

* tty.cfmakeraw() and tty.cfmakecbreak() now make a copy of the list of
  special characters before modifying it.

(cherry picked from commit 84e2096fbdea880799f2fdb3f0992a8961106bed)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>