Add namespaces filtering support in packages.config restore in nuget.exe and msbuild /t:restore

[nkolev92]

This task covers adding support in NuGet.exe, MSBuild.exe , VS.
A lot of the code is shared, but if need be, this task may be broken into smaller tasks.

I splitted into 2 pars. 2nd part is #10823

[nkolev92]

As discussed in the sync.

There are multiple entry points for packages.config restore, some documented here: https://github.com/NuGet/NuGet.Client/blob/dev/docs/debugging.md

• VS - https://github.com/NuGet/NuGet.Client/blob/17bc64685d0943a8b840aa5e18059fb402a47a8c/src/NuGet.Clients/NuGet.SolutionRestoreManager/SolutionRestoreJob.cs#L215
• nuget.exe - https://github.com/NuGet/NuGet.Client/blob/17bc64685d0943a8b840aa5e18059fb402a47a8c/src/NuGet.Clients/NuGet.CommandLine/Commands/RestoreCommand.cs#L261
• msbuild.exe restore - https://github.com/NuGet/NuGet.Client/blob/17bc64685d0943a8b840aa5e18059fb402a47a8c/src/NuGet.Core/NuGet.Build.Tasks/BuildTasksUtility.cs#L444

Eventually all of them end up in: https://github.com/NuGet/NuGet.Client/blob/dev/src/NuGet.Core/NuGet.PackageManagement/IDE/PackageRestoreManager.cs

The core is shared, but there are different entry points.

The commandline scenarios likely provide the fastest turnaround for implementation.

[nkolev92]

@erdembayar
I've just added back the total estimate of the effort to better track our progress :)