Should normative status and version extensions be inherited on SD elements? (Probably not?)

When SUSHI creates a profile, it clones the parent SD and then performs a series of steps, including removing all top-level extensions that should not be inherited by a profile (such as the normative status and normative version extensions). SUSHI does not currently remove these extensions from elements in the SD, but it seems like perhaps it should. We should investigate and modify as necessary.

Zulip discussion: https://chat.fhir.org/#narrow/stream/215610-shorthand/topic/Deterministic.20Output/near/408648034

Start by tracing the profile-generation steps where SUSHI clones the parent StructureDefinition and removes top-level extensions. Use the linked Zulip discussion to establish the expected inheritance behavior for extensions on elements, then inspect the relevant processing and tests. Done means the behavior is decided and the implementation and coverage match that decision.

Written by the indexing model from the issue text.