Add GCP related classes to the public xm_abc API.
Add GCP related classes to the public xm_abc API.

PiperOrigin-RevId: 388405463
Change-Id: I8595139a586248178f6ddc2ad71762a6004186bf
GitOrigin-RevId: 6f301bc9a657fda16c32044faae53a06714a45a7

deepmind/xmanager,deepmind/xmanager