Updating System.Collections.Immutable package reference to version 10.0.1

[MSLukeWest]

Description

Starting in VS 18.4, VS and MSBuild now reference this newer version of System.Collections.Immutable. Now, when the UWP test host runtime provider tries to load MSBuild assemblies it will fail, because the test platform's copy of System.Collections.Immutable doesn't have methods that MSBuild uses:

Microsoft.VisualStudio.TestPlatform.ObjectModel.TestPlatformException: Failed to launch testhost with error: System.AggregateException: One or more errors occurred. ---> System.TypeInitializationException: The type initializer for 'Microsoft.Build.Shared.XMakeElements' threw an exception. ---> System.MissingMethodException: Method not found: 'System.Collections.Frozen.FrozenSet`1<!!0> System.Collections.Frozen.FrozenSet.Create(System.Collections.Generic.IEqualityComparer`1<!!0>, System.ReadOnlySpan`1<!!0>)'.
   at Microsoft.Build.Shared.XMakeElements..cctor()

Related issue

Internal DevDiv bug 2692656

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