Describe the bug
--ssh-subsystem in the command line works, but config files are ignored.

Version(s) Affected
v0.4.0

To Reproduce

1. Set up a config file with SshSubsystem true
2. Run qcp --show-config and see that it shows as false with a source command-line, even though it wasn't entered on the command line.

Client configuration:
┌─────────────────────────┬─────────────┬─────────────────────────┐
│ field                   │ value       │ source                  │
├─────────────────────────┼─────────────┼─────────────────────────┤
[...]
│ SshSubsystem            │ false       │ command-line            │
[...]

Expected behavior
In the test case, the show-config output should show the value as true, source config file.

When not set in config file, the show-config output should show the value as false, source default.