[Feature Request]: PubSubIO.Write doesn't work in Batch pipelines in Go SDK

### What would you like to happen?

I was going through the source code of pubsub io and noticed that the `Write` function doesn't support Batch pipelines as mentioned in the code comments (see attached image)

I haven't personally verified it nor did I see a Github issue already open for this.

### Issue Priority

Priority: 3 (nice-to-have improvement)

### Issue Components

- [ ] Component: Python SDK
- [ ] Component: Java SDK
- [X] Component: Go SDK
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