Update appsettings schema with Kestrel and Logging configuration.

[JamesNK]

Work in progress. Temporarily removed existing properties.

[JamesNK]

@Tratcher @halter73 @davidfowl Please review the options and descriptions. I want to make sure everything is included and the comments and defaults are accurate.

There is no documentation for some of this (e.g. SNI in config) so I had to look at the code and figure out how it works.

[JamesNK]

@madskristensen The existing root properties in the schema use patternProperties, which started when you added the first version. I was wondering why this is done, and whether the common .NET properties I'm adding in this PR should do the same.

My theories are either:

1. patternProperties doesn't show up in autocomplete. This is desirable for properties like webOptimizer and elmah that aren't in most apps
2. Case-insensitivity

Should Logger/Kestrel/ConnectionStrings change to pattern properties?

[madskristensen]

@JamesNK Your first theory is the correct one. It was done such that optional 1st and 3rd party components could light up but wasn't being suggested by IntelliSense since the app might not use them at all. So, it was to avoid false positives but still have rich support for any component that wanted IntelliSense in appsettings.json.

[JamesNK]

@madskristensen Good to merge?

[madskristensen]

Thanks