Use cleaner reflection patterns

[brantburnett]

This can help improve performance, reduce runtime errors, and help support trimming if anyone wants to build smaller single-file applications.

An example:

https://github.com/dotnet/runtime/blob/ebba1d4acb7abea5ba15e1f7f69d1d1311465d16/src/libraries/System.Linq.Queryable/src/System/Linq/CachedReflection.cs#L539
https://github.com/dotnet/runtime/blob/ebba1d4acb7abea5ba15e1f7f69d1d1311465d16/src/libraries/System.Linq.Queryable/src/System/Linq/Queryable.cs#L263