Respect config generated by config-ssh

[code-asher]

I am not sure how feasible this is, but it seems more doable now that config-ssh uses wildcards. We generate a separate config because we want to add flags and options. Maybe we could read the SSH config and add anything we are missing? Would need to respect CODER_SSH_CONFIG_FILE as well.

Or, can we do something with includes? Or if we use a prefix like coder.vscode.* then it will just naturally inherit options.