Summary of changes:
- Moved end-to-end packaging script from TFS.
- Added e2e packaging steps to `build.ps1`.
- Added `AfterBuild` target to test extension projects publishing
build artifacts to a well-known location.
- Fixed `NuGet.Tests.psm1` module script to locate test extension
artifacts.
Contributes to NuGet/Home#3435, NuGet/Home#3519
FixesNuGet/Home#3185
- Added a parameter pointing to the right version of NuGet.Core for pdb publishing
- Added pdb to the command line package nuspec
- Minor script fixes
Added script replacing NuGet core floating version in NuGet clients
projects. Needed mostly in release branches to override more advanced
builds coming from myget feed/dev builds.