Ensure gitlab-workspace-proxy works with gitlab instance (GDK) with HTTPS enabled

Problem

At present, in the dev/local environment, gitlab-workspaces-proxy only works with gitlab instance (GDK) with HTTPS disabled. This is likely due to the fact that locally GDK supports HTTPS using a self-signed certificate. The gitlab-workspaces-proxy doesnt support this configuration at present.

Solution

• Perhaps we can take cues from how GDK supports this and mirror the same methodology in the gitlab-workspaces-proxy