* 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
Remove the functions which generated Nuget packages for Windows.
Add function New-UnifiedNugetPackage to generate nuget packages for each assembly with unix and windows runtimes.
Add function New-NuSpec and New-ReferenceAssembly for creating the required items forNew-UnifiedNugetPackage.
Add a sample for cross platform project with conditional compilation for Linux.
Add function Publish-NugetToMyGet to publish nuget packages to powershell.myget.or
Based on standard practices, we need to have a copyright and license notice at the top of each source file. Removed existing copyrights and updated/added copyright notices for .h, .cpp, .cs, .ps1, and .psm1 files.
Updated module manifests for consistency to have Author = "PowerShell" and Company = "Microsoft Corporation". Removed multiple line breaks.
Separate PR coming to update contribution document for new source files: #6140
Manually reviewed each change.
Fix#6073
