title: Use environment appsettings.{Environment}.json vs hardcoding in file name or db connection details in CreateHostBuilder method?
body: <p>Using ef core it's possible to get everything working and run the dotnet ef migrations command line tool but Program.cs required the method</p>
  
  <pre><code>public static IHostBuilder CreateHostBuilder(string[] args)
  </code></pre>
  
  <p>The only thing that isn't ideal is storing database settings in a development json file then having to hardcode the development json file name in that method or hardcoding the db connection details into that method. When checking</p>
  
  <pre><code>context.HostingEnvironment.IsDevelopment() //always returns false
  </code></pre>
  
  <p>it is never correct or doesn't get set properly so we can't use context.HostingEnvironment.EnvironmentName as a variable either. Is there a way in the CreateHostBuilder method to load the proper app settings json file and configure/setup the environment for running the ef migrations command line tools vs hardcoding?</p>