Support for data type-based sub elements in element identification logic

Currently, MADFSH searches the parent profile for the element target path and logs an error if it doesn't find the element. However, sometimes the element target path will be valid, but the sub-element referred to will be defined within the type of a parent. For example, `Condition.abatementPeriod.low`: abatementPeriod is a potential polymorphic element for `abatement[x]` that is of type Period, with a `low` subelement. It is therefore valid even though it does not appear in the snapshot list for Condition. The element identification logic in MADFSH should recognize this and not error, ideally adding the target element as must support.