Support sourceUri passed on nuget restore/install and dotnet restore package or other equivalent commands

[erdembayar]

Details about Problem

NuGet product used (NuGet.exe | Visual Studio | MSBuild.exe | dotnet.exe):

Product version: N/A

Worked before? If so, with which NuGet version:

Repro steps and/or sample project

Address Karteek's comment about there are chances that users might pass -source option to the restore command.
To support this we may need small changes SearchTree, PackageDownloader.cs and PackageNamespacesConfiguration.cs
files.

Verbose Logs

[erdembayar]

@aortiz-msft @nkolev92
It looks, I started working on this issue too early. I created new unit tests but I better to work on this after I complete #10738

[nkolev92]

@erdembayar

Are you planning to validate both packages.config and PackageReference with this one?

cc @kartheekp-ms

[erdembayar]

@nkolev92
Packages.config is yes, not sure about PackageReference, but I'll try to validate both.

[nkolev92]

I see dotnet add package is in the name, but that only handles PR.

I'll let you and @kartheekp-ms decide, but consider splitting up the work in 2 issues.

[nkolev92]

For complete here are the scenarios of interest PC & PR.

• nuget.exe restore -source
• dotnet.exe restore -source
• RestoreSources in csproj for PackageReference
• nuget.exe install -source
• dotnet add package -source
• PMC install-package -source
• PMC update-package -source

Note that the last 2 are not relevant in PackageReference. There's a warning message when you try that.

[erdembayar]

@nkolev92
Could you be able to give more context on RestoreSources in csproj for PackageReference? How does it work?

[nkolev92]

You can do the following and it overrides the package sources specified in the nuget config.

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0</TargetFramework>
    <RestoreSources>https://api.nuget.org/v3/index.json</RestoreSources>
  </PropertyGroup>
  
  <ItemGroup>
    <PackageReference Include="nuget.common" Version="4.9.1"/>
  </ItemGroup>

</Project>

[erdembayar]

@nkolev92 @kartheekp-ms
I noticed there's another option p:RestoreAdditionalProjectSources besides p:RestoreSources.
Do we need to take into account?

[nkolev92]

@erdembayar

Yes, but I'd expect they'd be automatically handled.
RestoreSources, RestoreAdditionalProjectSources are all merged early on.
If your tests work with RestoreSources, I'd expect them to work with RestoreAdditionalProjectSources as well.

[erdembayar]

I created follow up issue for dotnet add package --source scenario #11140