for types that result from merged allOf constructs, implement conversion to the component types

[ahl]

If we see an allOf, we'll merge that into a type that's the intersection of the components of the subschema array. In such a situation it would be nice to have conversion methods:

pub struct MergedTypes { }

impl From<MergedType> for ComponentType1 { }
impl From<MergedType> for ComponentType2 { }