[AIBundle] Streaming responses missing from the profiler

[valtzu]

While working on the streaming demo (#118), I discovered streaming AI responses do not show up in the profiler, even though the related HTTP requests / responses do show up there.

Looks like the issue with streaming responses missing in the profiler is due to 2 issues:

1. DataCollector does not implement LateDataCollectorInterface – this is an easy fix
2. StreamResponse holds a \Generator and thus, is not serializable