Expose a function findRemappedElementClass

[nick4598]

Transformer allows remapping of element classes, but we can't search the already added remappings like we can with something like an element Id remapping.
In transformer repo:
Element ID Remapping:
remapElement(sourceId, targetId)
findTargetElementId(sourceId) => targetId
ClassFullName Remapping:
remapElementClass(sourceClassFullName: string, targetClassFullName: string)
findRemappedElementClass(sourceClassFullName)<--- THIS DOESN'T EXIST