Handle Non-Zero USS Command Exit Codes in UssCmd

[frankgiordano]

Currently, UssCmd.issueCommand() waits for the SSH command to complete and returns the command output as a String, but it does not inspect the USS command's exit status.

A USS command can complete successfully from the SSH/JSCH perspective while still returning a non-zero exit code, indicating that the command itself failed.

This behavior should be evaluated and potentially updated so that a non-zero USS exit code results in a UssCmdException.