Look into whether we need updates to enable/disable JsonSerializerIsReflectionEnabledByDefault

[rolfbjarne]

Refs:

• Disable JsonSerializer.IsReflectionEnabledByDefault on PublishTrimmed=true runtime#84378
• Add a JsonSerializerIsReflectionEnabledByDefault property sdk#31626

Depending on what happens with these issues, we might have to update something on our end.

So this is just an issue to not forget to do whatever needs to be done once we know if anything actually needs to be done.

[rolfbjarne]

Looks like we need to set the property to true.

Ref: dotnet/maui#16038
Ref: dotnet/runtime#90395

[rolfbjarne]

We should also add a trivial test:

System.Text.Json.JsonSerializer.Serialize(42)

[rolfbjarne]

Fixed in f8b7b53.