refactor(gemini-live): bring tool-result handling in line with the canonical realtime pattern

Lays groundwork for cancel_on_interruption=False support on Gemini Live by
restructuring _process_completed_function_calls to match the shape used by
AWSNovaSonicLLMService and OpenAIRealtimeLLMService in #4441: a single-pass
forward iteration over raw context messages that detects async-tool
messages via async_tool_messages.parse_message and routes them — started
skipped silently, intermediate logged-as-error and surfaced via push_error,
final delivered via the formal FunctionResponse channel.

Replaces the prior two-pass structure that went through the adapter for
sync results — the service now uses a lightweight self._tool_call_id_to_name
map (populated when the model issues tool calls) for the name lookup the
adapter used to provide. Extracts a new GeminiLLMAdapter.to_function_response_dict
static method for the dict-coercion logic that wraps non-dict tool returns
as {value: <result>} for Gemini's FunctionResponse.response field; the
adapter's existing inline copy in _from_standard_message uses it too.

Example consolidation:

- Folds realtime-gemini-live-function-calling.py into the base
  realtime-gemini-live.py example so the base exercises function calling
  out of the box (matching realtime-openai.py and realtime-aws-nova-sonic.py).
- Renames realtime-gemini-live-vertex-function-calling.py to
  realtime-gemini-live-vertex.py, mirroring the consolidation.
- Adds realtime-gemini-live-async-tool.py.
- Updates scripts/evals/run-release-evals.py for the renames.

This commit alone doesn't make cancel_on_interruption=False fully work on
Gemini Live — additional investigation is pending. This is foundational
work to be built on.

scripts/evals/run-release-evals.py

@@ -223,12 +223,11 @@ TESTS_REALTIME = [
     # ("realtime/realtime-azure.py", EVAL_WEATHER),
     ("realtime/realtime-openai-text.py", EVAL_WEATHER),
     ("realtime/realtime-openai-live-video.py", EVAL_VISION_CAMERA),
-    ("realtime/realtime-gemini-live.py", EVAL_SIMPLE_MATH),
+    ("realtime/realtime-gemini-live.py", EVAL_WEATHER),
     ("realtime/realtime-gemini-live-local-vad.py", EVAL_SIMPLE_MATH),
-    ("realtime/realtime-gemini-live-function-calling.py", EVAL_WEATHER),
     ("realtime/realtime-gemini-live-video.py", EVAL_VISION_CAMERA),
     ("realtime/realtime-gemini-live-google-search.py", EVAL_ONLINE_SEARCH),
-    ("realtime/realtime-gemini-live-vertex-function-calling.py", EVAL_WEATHER),
+    ("realtime/realtime-gemini-live-vertex.py", EVAL_WEATHER),
     ("realtime/realtime-aws-nova-sonic.py", EVAL_SIMPLE_MATH),
     ("realtime/realtime-ultravox.py", EVAL_ORDER),
     ("realtime/realtime-grok.py", EVAL_WEATHER),