I don't have gcloud, so could you please explain how this PR makes parseGCPSSHCmd return a host with a username?

The dryRumCmd( gcloud compute ssh --dry-run InstanceName ) (Line 538) return the command used to ssh to the instance directly(without gcluod sdk).
So, the command:
localUser@localhost:~$ gcloud compute ssh --dry-run myInstance
returns something like(comment mentioning it at line 553) :
ssh **ssh flags** [email protected]

Now this works good if we(sshcode) wanna use the current localUser to ssh, so if we use
localUser@localhost:~$ gcloud compute ssh --dry-run remoteUser@myInstance
returns something like :
ssh **ssh flags** [email protected]

Before my commit, we were ignoring this username (comment mentioning it at line 556), by returning the userIP, we retain the username provided by the user and ssh to the correct user on the instance.

Ah, thanks for pointing that out, I was reluctant on remove that part becuase it was checking that the IP Address was valid, your comment made me to do some digging, and yes, it NEEDS to be gone, its not just unnecessory, but a bug on its own.
I found out that when an external IP is not assigned to the GCP instance we are trying to ssh to, the dry-run command returns something like this:
ssh **sshFlags** sscsps@compute.{{instanceIDAtGCP}}
As we can see that the last part is not a valid IP and will thus fail that check, but this command is valid(well, there's a bug in gcloud sdk at this point that gives invalid sshFlags at this point in a certain case, will be reporting that to google soon, not throughly tested yet), we can ssh with the dry-run command provided(when corrected),
So, yeah, we should remove that.

Will push the change soon and add this to first message.

Ok, so I was testing my changes out for instances with no external IP, and I found that instances with no external IP addresses cant connect to internet.
This means downloading the code-server on the instance is not possible(at least i dont know how to do it). So I think we'll have to download it on our local machine and scp it over to the instance.
I think that is out of scope for this PR, will work on it and raise new PR when I do that.

Looks good to me. These commits need to be signed with PGP before I can merge them though.

Signed :)