Expose Helpers for google.cloud.aiplatform.v1.ITensor

In the context for developing streaming chat services with the nodejs client library I believe it would be very helpful to expose helpers to automatically generate ITensors ( https://cloud.google.com/nodejs/docs/reference/aiplatform/latest/aiplatform/protos.google.cloud.aiplatform.v1.itensor)

This is useful for situations such as: https://cloud.google.com/vertex-ai/docs/generative-ai/learn/streaming;