Changes:
* Fix broken tests and VS solutions caused by source code reorganization
* Add a check to validate generated code and solutions on PRs
* backport some source code reorg to src/Identity
* Fix startvs.cmd if you've already run build.ps1
* Add PR checks for tests on Linux/macOS
* Skip broken Nginx tests
* Add conditions to skip IIS tests on non-Windows platforms
Nate McMaster