[Feature] Add support for SSH IdentityAgent

[CrazyVito11]

Issue
I use 1Password as my identity agent in order to authenticate SSH requests, but GittyUp doesn't seem to support this if I add it to the ssh config.

I've added the IdentityAgent to my SSH config file and works properly if I execute GIT commands via the terminal, but not via GittyUp. Maybe it doesn't load the config properly?

Host *
        IdentityAgent ~/.1password/agent.sock

Workaround
I currently use a workaround by viewing and creating commits using the UI, but fetching/pulling and pushing via the terminal.

Requested functionality
That support for IdentityAgents is added or that the possible bug in the SSH config support is fixed.

Please let me know if you need any more information!

[CrazyVito11]

It seems like it suddenly started to work, so it was probably a misconfiguration of the 1Password SSH agent on my end. 😅

I did make a change to my system yesterday for Tabby, as that also didn't seem to recognize the 1Password agent.
After then consulting the 1Password documentation, I found that applying the SSH_AUTH_SOCK globally fixed the issue for Tabby, and that is also probably why GittyUp suddenly started to work.

The command I ran can be found here: https://developer.1password.com/docs/ssh/agent/compatibility#configure-ssh_auth_sock-globally-for-every-client-1

I will close this issue now, and hope that this information might also help someone else in the future. 👍