Remove hard-coded paths in Functions to app setting configuration

[briansok71]

All paths to FHIR service, service bus queues, data lake containers should be configured in Function app settings instead of hard-coded. The functions can read from app settings configuration using environment variables, but prefer dependency injecting IConfiguration (see example below):

Startup.cs

public class Startup : FunctionsStartup
    {
        public override void Configure(IFunctionsHostBuilder builder)
        {
            // DI function configuration
            IConfiguration configuration = new ConfigurationBuilder()
                .AddJsonFile(Constants.Config.LocalSettings, optional: true, reloadOnChange: false)
                .AddEnvironmentVariables()
                .Build();
            builder.Services.AddSingleton<IConfiguration>(configuration);

SomeFunction.cs

public class SomeFunction
    {
        private readonly IConfiguration _configuration;
        private ILogger _logWriter;

        // read DI in constructor
        public SomeFunction(IConfiguration configuration, IHttpClientFactory httpClientFactory)
        {
            _configuration = configuration;
            _healthChecker = new HealthChecker(httpClientFactory);
        }

[briansok71]

Michael and Nicholas can implement on the 3 Azure Function apps

[bennettn4]

Values were never hard-coded in the function apps Application configuration was done per Function App in their Configuration In conjunction with the work in CDCgov/data-exchange-fhir#148 configuration has been moved to a single consolidated Azure App Configuration store