refactor: process all streaming events for forward compatibility

Changes based on review feedback from @karpetrosyan:

1. Removed MESSAGE_EVENTS filtering - now processes any event received
2. Removed early response closing (response.close/aclose) - will be ported to codegen
3. Removed performance test file - no longer applicable

This change improves forward compatibility by processing any event type
the API sends, rather than filtering to a predefined set. The new
structure handles completion, ping, and error events explicitly, while
processing all other events generically.

Closes review feedback in #993

Author: fede-kamel