Members Refreshed

Extension used by a server to indicate to a client when the members in a dynamic group were last updated. For example, the following extension would indicate that the group members were last updated January 1st 2024: ``` "Extension" : [{ "url" : "http://hl7.org/fhir/uv/bulkdata/StructureDefinition/members-refreshed", "valueDateTime" : "2024-01-01T13:28:17-05:00" }] ```