Align with new backend API

[arey]

The PR https://github.com/spring-petclinic/spring-petclinic-rest/pull/52 introduce some changes to the backend API:

• date format have changed to RFC-3339
• some bidirectional ids have been removed.
• search by lastname API has changed
• The /pets resource move to /owners/{ownerId}/pets

Thoses changes may be reported to the Angular frontend.

[arey]

@simrin051 you may take this issue if you want

[simrin051]

Thanks @arey

[gerardorosiles]

Hi, not sure if issue is related to what I am seeing using the Docker image for the Angular frontend. I get 400 response error for the backend endpoints to add a veterinarian, a new type of pet and a new type of speciality.