Added default ILoggingBuilder extension

[snargledorf]

For situations where configuration is under the default "Logging" section. Also accepts an optional configure options action.

Usage: loggingBuilder.AddFile()

[snargledorf]

I did just think of something that is pushing me to close this pull request.

With this implementation, in the event the "File" configuration is not present under the "Logging" configuration, the CreateFromConfiguration method will return null. This causes an exception to be thrown when building the service collection.

The expectation for default extensions such as this is that it will construct the service (In this case an ILoggerProvider) with a default configuration. Since don't have a default path for the log file, we cannot setup a logging provider with a default configuration.

Unless in the future a default log file is defined, this has the potential to break apps unintentionally when changing logging configuration (IE. Removing the "File" section), which shouldn't happen.

[snargledorf]

I updated the PR with a potential solution.

Now if the FileLoggerProvider fails to be built, a NullLoggerProvider is returned in its place. This isn't my favorite solution, but it does technically fix the exception and is more in line with expected behavior.