RuntimeFeature.IsSupported("EmitIL") would be a useful feature check. #24467
Description
Whether one can emit IL or not is a significant difference between platforms, that impacts on the best approach to some problems, so it would be useful if RuntimeFeature could be queried about it.
This should close #17973 as well, which wishes to be able to enquire as to whether LamdbaExpression.Compile() can emit IL, which in turn depends on that feature.