Deserializing System.Collections.Immutable types with JsonSerializer is not linker safe

[layomia]

A NullReferenceException is thrown when deserialization of any of these collection types is attempted, due to the various CreateRange methods being trimmed out e.g. https://docs.microsoft.com/dotnet/api/system.collections.immutable.immutablelist.createrange.

[eerhardt]

@layomia - did we fix this? Can it be closed now?

[layomia]

@eerhardt yes - this was fixed in #38595.