Add host_proxy_cmd parameter to SSHHook and SFTPHook

[ajitg25]

closes: #43636

Added the host_proxy_cmd parameter to SSHHook and SFTPHook.
Added unit tests to validate the changes in SSHHook and SFTPHook.

[boring-cyborg]

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[potiuk]

LGTM

[potiuk]

Tests need to be fixed @ajitg25 - apparently those tests depend on ncat being available in the environment, and we should not rely on it.

[ajitg25]

Tests need to be fixed @ajitg25 - apparently those tests depend on ncat being available in the environment, and we should not rely on it.

@potiuk Apologies, it was a miss from my side. Now, I have fixed the unit test cases in both files. PTAL!!

test_ssh

test_sftp

[boring-cyborg]

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