IssueTracker

-- Requested enhancement description (What would you like to accomplish?)
User metadata labels for Vertex AI and AI platform for billing export feature to be made available in the GCP.

-- Detailed functionality description
User metadata labels for Vertex AI(models, endpoints) and AI Platform feature needs to be made available for billing export so that it can help to export the metadata labels for billing purposes to BigQuery.

Other information (workarounds you have tried, documentation consulted, etc):
[1] - https://cloud.google.com/resource-manager/docs/creating-managing-labels#common-uses     
[2] - https://cloud.google.com/resource-manager/docs/creating-managing-labels#label_support   
[3] - https://cloud.google.com/ai-platform/training/docs/resource-labels