conversionOperators

The user-defined conversion operators between the types in
typeLevelInHierarchy. Convert(System.Linq.Expressions.Expression,System.Type) finds one by reflecting over the target type, and a trimmed or NativeAOT build has no
metadata for an operator nothing referenced: double -> Complex came back as "no
coercion operator is defined between types", so a compiled expression mixing an integer
literal with a complex argument threw where the JIT build answered. Naming them keeps
them, and spares the lookup.
https://github.com/asc-community/AngouriMath/issues/363