Support parsing of the ssh config file on Windows so step-ssh can use multiple ssh agents

[drbrowen]

Hello!

• Vote on this issue by adding a 👍 reaction
• If you want to implement this feature, comment to let us know (we'll work with you on design, scheduling, etc.)

Issue details

If OpenSSH on Windows is configured to use an agent other than the default, step ssh commands will not find the correct pipe to the ssh-agent

Why is this needed?

Alternate ssh-agents enable other software programs, such as pageant, PuTTY, WinSCP, and others to function with step ssh login on Windows.