Finish Log Filter Design

Throughout the code we create loggers all over with custom log categories. However currently have some temporary code [here](https://github.com/Azure/azure-functions-host/blob/088a18e624cd3e4dfb68847c3045ed5611ad6f48/src/WebJobs.Script/Utility.cs#L408) which is putting a category filter in place, that filters to a small whitelist.

I introduced a new log category for my component and didn't understand why my logs weren't being written. It took a long time for me to track it down to this offending bit of code. That's 30 minutes of my life I'll never get back :(

There is a TODO in the code. We should finish this.