Gauge associations should be added by default

[sswaroopgupta]

When Gauge is installed the IDE features should be available even when other VSCode plugins are installed.

"files.associations": {
        "*.spec": "gauge",
        "*.cpt": "gauge"
    }

should be added by default to the settings

[nehashri]

Approach to be followed
When Gauge VSCode plugin is started within a Gauge project workspace, the above settings should be added to the workspace settings. This should be done automatically without prompting the user to add the settings.

[nehashri]

should be available in nightly >= 23-4-18