Update hosting configuration to enable the support for Decoupling workers

[surgupta-msft]

We will use hosting configuration to onboard workers to the Decoupling Workers feature. This allows us to do worker by worker onboarding to the feature i.e. we don’t need to redeploy the Host if a new worker onboards to the feature or any worker needs to temporarily disable the feature.

We will add a section in the Hosting configuration to specify workers location at the site extensions path. For those workers, which are not available via site extensions (and hence not onboarded to decoupling workers feature), there won’t be any entry in the config file and hence we will use the default directory flow for them.

{ 
    "languageWorkers": 
    { 
        "python": "c:\home\SiteExtensions\python", 
        "java": "c:\home\SiteExtensions\java"  
        // nothing for the languages not available via site extensions 
    } 
}