Support the *.Development.json config file pattern for connections and parameters files

[TWolversonReply]

When we write .NET apps, the default template includes an appsettings.json and an appsettings.Development.json, where the asp.net middleware knows to let the development settings override only when running locally. App Service sets an environment variable for the .net environment that deselects the development settings and falls back to the standard appsettings.

This would be an ideal pattern to follow for parameterising the connections.json where built-in connectors use managed identity, that is known not to work locally. Typical recommendations to achieve local development are to define another connections.json using raw authentication. It would reduce development friction to have a standard way to do this built-in that works the same way as web apps on Azure.