run_cmd() is synchronous. Now that all commands are asynchronous, we
can await it, so rewrite it to be asynchronous, too.
Other changes:
- Make it return stderr as well in case its needed
- Drop into a pseuto-tty if
- cmd_input == "mode:interactive" or
- cmd_input == "mode:auto" and stdin is a TTY
- Add argument env, defaulting to None. If it's a dict, it will be
the environment the command is run in
This entails making all functions using run_cmd() async, too,
including run_curl(), get_username() and get_password().
Signed-off-by: Jan Lindemann <jan@janware.com>
