editor: save and reset terminal after calling EDITOR
When EDITOR is invoked to modify a commit message, it will likely
change the terminal settings, and if it misbehaves will leave the
terminal output damaged as shown in a recent report from Windows
Terminal[1]
Instead use the functions provided by compat/terminal to save the
settings and recover safely.
[1] https://github.com/microsoft/terminal/issues/9359
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>