System logs should include effective configuration at the root level

Had a case where the customer was misusing DI and overriding the IConfiguration object. This was resulting in some host.json settings not being read. Specifically the functionTimeout setting. From log inspection, it was not obvious that the function timeout was not being picked up. If we were logging the effective config at the root level, this would have been clearer.

No file, test, or entry point is named in the issue. Start by locating the Azure Functions host's system logging path and configuration handling; done means the effective root-level configuration, including functionTimeout, is visible in logs when IConfiguration has been overridden.

Written by the indexing model from the issue text.