feat: support realtime input config

Merge https://github.com/google/adk-python/pull/981

issue: https://github.com/google/adk-python/issues/982

This pull request introduces a new configuration option, `realtime_input_config`, to the `RunConfig` class.

**Reason for this change:**

Currently, there is no direct way to configure real-time audio input behaviors, such as Voice Activity Detection (VAD), for live agents through the `RunConfig`. The Gemini API documentation (specifically [Configure automatic VAD](https://ai.google.dev/gemini-api/docs/live#configure-automatic-vad)) outlines parameters for VAD that users may want to customize.

This change enables users to pass these real-time input configurations, providing more granular control over the audio input for live agents.

**Changes made:**

- Added a new optional field `realtime_input_config: Optional[types.RealtimeInputConfig]` to the `RunConfig` class.
- The docstring for `realtime_input_config` has been added to explain its purpose.

**Example Usage (Conceptual):**

While the specific structure of `types.RealtimeInputConfig` would define the exact parameters, a user might configure it like this:

```python
# (Assuming types.RealtimeInputConfig and types.VadConfig are defined elsewhere)
# import your_project.types as types

run_config = RunConfig(
    # ... other configurations ...
    realtime_input_config=types.RealtimeInputConfig(
        automatic_activity_detection =types.AutomaticActivityDetection(
            # VAD specific parameters like sensitivity, endpoint_duration_millis etc.
            # based on https://ai.google.dev/gemini-api/docs/live#configure-automatic-vad
        )
        # Potentially other real-time input settings could be added here in the future
    )
)
COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/981 from ammmr:patch-add-realtime-input-config b2e17fbf5742d264029ad49bf632422b5c5b1e0a
PiperOrigin-RevId: 770797640

src/google/adk/agents/run_config.py

@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from __future__ import annotations
+
 from enum import Enum
 import logging
 import sys
@@ -68,6 +70,9 @@ class RunConfig(BaseModel):
   input_audio_transcription: Optional[types.AudioTranscriptionConfig] = None
   """Input transcription for live agents with audio input from user."""
 
+  realtime_input_config: Optional[types.RealtimeInputConfig] = None
+  """Realtime input config for live agents with audio input from user."""
+
   max_llm_calls: int = 500
   """
   A limit on the total number of llm calls for a given run.

src/google/adk/flows/llm_flows/basic.py

@@ -65,6 +65,9 @@ class _BasicLlmRequestProcessor(BaseLlmRequestProcessor):
     llm_request.live_connect_config.input_audio_transcription = (
         invocation_context.run_config.input_audio_transcription
     )
+    llm_request.live_connect_config.realtime_input_config = (
+        invocation_context.run_config.realtime_input_config
+    )
 
     # TODO: handle tool append here, instead of in BaseTool.process_llm_request.
 

src/google/adk/models/gemini_llm_connection.py

@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from __future__ import annotations
+
 import logging
 from typing import AsyncGenerator