L2VPN SDX Internal Operation attributes last_modified and creation_date

[italovalcy]

Hi,

According to the specification (https://sdx-docs.readthedocs.io/en/latest/specs/provisioning-api-1.0.html#sdx-internal-operation):

Once a SDX L2VPN service is provisioned, the SDX Controller must add the following attributes to the L2VPN. These attributes must be exported to the SDX user when queries are submitted:

• creation_date: the service creation time using ISO860, following the same format specified by the AtlanticWave-SDX 2.0 Topology Data Model specification.
• last_modified: the datetime of the last modification performed on the L2VPN. Initial value is 0.