AdministrativeInformation: add createdAt and updatedAt attributes

[BirgitBoss]

Is your feature request related to a problem? Please describe.
There are requirements requesting search capabilities via date or date ranges an AAS or Submodel was created, see for example admin-shell-io/aas-specs-api#176 or eclipse-tractusx/sldt-digital-twin-registry#466

Additionally we also need administrative information for AssetAdministrationShellDescriptors (for SubmodelDescriptors it might not be needed).

Note: AssetAdministrationShellDescriptor/administration is the administrative information for the AssetAdministrationShell, not for the Descriptor.

Describe the solution you'd like
Add the following optional attributes to AdministrativeInformation:

• createdAt
• updatedAt

with type dateType and add

• constraint requiring that the format is YYYY-MM-DDTHH:MM:SSZ

Add the following optional attributes to AssetAdministrationShellDescriptor:

• descriptorCreatedAt
• descriptorUpdatedAt

or

• descriptorAdministration with existing type AdministrativeInformation