Better handle previews identifiers in the toolbar

[slemeur]

We have introduce the new toolbar with #3519;

We need to improve the identifier that we are using to differenciate the different servers that are running in the workspace.

At this moment we display the previewURL.

But this is not really helping the user. The ephemoral port is not really relevant and helpful.

We need to find a solution so that it's clearer for the end-user.

The idea would be to display the server that is running. For example:

• dev-machine:8080
• dev-machine:9000