Allow passing SSH arguments to the Zed CLI through env vars

[sagikazarmark]

I'd like to pass an identity file to Zed when opening an SSH remote directory without having to define an ssh connection in Zed:

ZED_SSH_ARGS="-i path/to/identity-file" zed ssh://...

Use case: using Zed with any other tool that automatically generates/downloads SSH keys (eg. Google Cloud, iximiuz Labs, etc) and allow scripting with Zed when using such tools.