Update .NET SDK to 10 GA

[jjonescz]

Fixes errors which cause for example most of MSBuild source code to be missing from source.dot.net currently.

D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5): You must install or update .NET to run this application. [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5):  [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5): App: D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\bincore\csc.exe [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5): Architecture: x64 [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5): Framework: 'Microsoft.NETCore.App', version '10.0.0' (x64) [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5): .NET location: C:\hostedtoolcache\windows\dotnet [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5):  [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5): The following frameworks were found: [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5):   10.0.0-rc.1.25451.107 at [C:\hostedtoolcache\windows\dotnet\shared\Microsoft.NETCore.App] [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5):  [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5): The following frameworks for other architectures were found: [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5):   x86 [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5):     6.0.40 at [C:\Program Files (x86)\dotnet\shared\Microsoft.NETCore.App] [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5):     8.0.22 at [C:\Program Files (x86)\dotnet\shared\Microsoft.NETCore.App] [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5):     9.0.11 at [C:\Program Files (x86)\dotnet\shared\Microsoft.NETCore.App] [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5):  [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5): Learn more: [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5): https://aka.ms/dotnet/app-launch-failed [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5):  [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5): To install missing framework, download: [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]
D:\a\_work\1\s\bin\repo\msbuild\.dotnet\sdk\10.0.100\Roslyn\Microsoft.CSharp.Core.targets(84,5): https://aka.ms/dotnet-core-applaunch?framework=Microsoft.NETCore.App&framework_version=10.0.0&arch=x64&rid=win-x64&os=win10 [D:\a\_work\1\s\bin\repo\msbuild\src\Framework\Microsoft.Build.Framework.csproj]

Validation build: https://dev.azure.com/dnceng/internal/_build/results?buildId=2850963&view=results