Adjust paths so that Gitpod (original) mounting points match devconta…

…iner

mounting points.

In the medium term, we should remove paths and that are specific to the
original Gitpod implementation.

.devcontainer/devcontainer.json

@@ -34,5 +34,6 @@
             "label": "Application",
             "onAutoForward": "openPreview"
         }
-    }
+    },
+    "postCreateCommand": "mkdir -p /workspace && ln -s /workspaces /workspace/gitpod"
 }