Add access to webhostenvironment

[jkone27]

CEs element or other configuration parts requiring IWebHostEnvironment instances can have access to it, for example

 [<CustomOperationAttribute("custom_bootstrap")>]
    member this.CustomBootstrap (state : ApplicationState) =

        let service (services : IServiceCollection) =

            services.CustomBoostrap(
                ApplicationBuilder.WebHostEnvironment, //// <<< USED HERE
                (Config.getConfiguration(services)),
                fun opt ->
                    opt.ApplicationInformation.ApplicationName <- "Acme.WebApi.Template.ApplicationName"
                    opt.ApplicationInformation.ApplicationGroup <- "Acme.WebApi.Template.ApplicationGroup"
            )

        {  state with
            ServicesConfig = service::state.ServicesConfig
            }