Provide additional call site context when exception originates in gRPC

Errors like `RESOURCE_EXHAUSTED` to not provide contextual information about where the exception occurs in a user's application:

```
Error: 8 RESOURCE_EXHAUSTED: Bandwidth exhausted
at Object.callErrorFromStatus (/root/repo/node_modules/@grpc/grpc-js/build/src/call.js:30:26)
at Http2CallStream. (/root/repo/node_modules/@grpc/grpc-js/build/src/client.js:96:33)
at Http2CallStream.emit (events.js:215:7)
at Http2CallStream.EventEmitter.emit (domain.js:476:20)
at /root/repo/node_modules/@grpc/grpc-js/build/src/call-stream.js:75:22
at processTicksAndRejections (internal/process/task_queues.js:75:11) {
code: 8,
details: 'Bandwidth exhausted',
metadata: Metadata { internalRepr: Map {}, options: {} },
note: 'Exception occurred in retry method that was not classified as transient'
}
```

It would be nice if we knew the specific method call that triggered exceptions.

Refs: https://github.com/googleapis/nodejs-datastore/issues/525