Changes:
* Remove obsolete targets which are unnecessary now that this repo no longer builds git submodules in a separate build process
* Remove the need for static analysis of 'ArtifactInfo' items
* Simplify how the code signing task is configured
* Remove unused repo tasks
* Remove duplicate lists of external dependencies and packages to be produced
* Remove obsolete build definition
* Remove obsolete build script parameters
* Add VisualStudioSetupOutputPath
- #3754
- remove `#if`'s for multi-targeting where source is never multi-targeted
- left `StreamPipeReader`, `StreamPipeWriter` and their test classes alone because they're moving to CoreFx
Replaces package references the following packages with local code:
Microsoft.AspNetCore.Certificates.Generation.Sources
Microsoft.Extensions.CopyOnWriteDictionary.Sources
Microsoft.Extensions.ClosedGenericMatcher.Sources
Microsoft.Extensions.ObjectMethodExecutor.Sources
Microsoft.Extensions.PropertyActivator.Sources
Microsoft.Extensions.PropertyHelper.Sources
Microsoft.Extensions.RazorViews.Sources
Microsoft.Extensions.SecurityHelper.Sources
Microsoft.Extensions.StackTrace.Sources
Microsoft.Extensions.WebEncoders.Sources
John Luo
Justin Kotalik
Nate McMaster
Javier Calvarro Nelson
Pavel Krymets
Hao Kung
Doug Bunting
Nate McMaster