* Build Update
- Change `TargetFramework` to `netcoreapp2.1` and removed unnecessary `RuntimeFrameworkVersion` from `PowerShell.Common.props`
- Update dotnet SDK to 2.1.300-rc1-008662
- Update `TypeGen` target in `Build.psm1` to work with 2.1
- Rename macOS runtime to `osx-x64` as the old build logic expects 10.12 and breaks running on 10.13 system.
- Remove `PackageReference` to `System.Memory` as it's part of dotnetcore 2.1
- Update search for `crossgen` executable to find the matching version
* Test Update
- Update test tools `WebListener` to latest `asp.net core`
- Marked `AuthHeader Redirect` tests as `Pending` due to change in CoreFX
