feat: add BigQuery first-party tools.

These tools support getting BigQuery dataset/table metadata and query results.

PiperOrigin-RevId: 764139132

contributing/samples/bigquery/README.md

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+# BigQuery Tools Sample
+
+## Introduction
+
+This sample agent demonstrates the BigQuery first-party tools in ADK,
+distributed via the `google.adk.tools.bigquery` module. These tools include:
+
+1. `list_dataset_ids`
+
+  Fetches BigQuery dataset ids present in a GCP project.
+
+1. `get_dataset_info`
+
+  Fetches metadata about a BigQuery dataset.
+
+1. `list_table_ids`
+
+  Fetches table ids present in a BigQuery dataset.
+
+1. `get_table_info`
+
+  Fetches metadata about a BigQuery table.
+
+1. `execute_sql`
+
+  Runs a SQL query in BigQuery.
+
+## How to use
+
+Set up environment variables in your `.env` file for using
+[Google AI Studio](https://google.github.io/adk-docs/get-started/quickstart/#gemini---google-ai-studio)
+or
+[Google Cloud Vertex AI](https://google.github.io/adk-docs/get-started/quickstart/#gemini---google-cloud-vertex-ai)
+for the LLM service for your agent. For example, for using Google AI Studio you
+would set:
+
+* GOOGLE_GENAI_USE_VERTEXAI=FALSE
+* GOOGLE_API_KEY={your api key}
+
+### With Application Default Credentials
+
+This mode is useful for quick development when the agent builder is the only
+user interacting with the agent. The tools are initialized with the default
+credentials present on the machine running the agent.
+
+1. Create application default credentials on the machine where the agent would
+be running by following https://cloud.google.com/docs/authentication/provide-credentials-adc.
+
+1. Set `RUN_WITH_ADC=True` in `agent.py` and run the agent
+
+### With Interactive OAuth
+
+1. Follow
+https://developers.google.com/identity/protocols/oauth2#1.-obtain-oauth-2.0-credentials-from-the-dynamic_data.setvar.console_name.
+to get your client id and client secret. Be sure to choose "web" as your client
+type.
+
+1. Follow https://developers.google.com/workspace/guides/configure-oauth-consent to add scope "https://www.googleapis.com/auth/bigquery".
+
+1. Follow https://developers.google.com/identity/protocols/oauth2/web-server#creatingcred to add http://localhost/dev-ui/ to "Authorized redirect URIs".
+
+  Note: localhost here is just a hostname that you use to access the dev ui,
+  replace it with the actual hostname you use to access the dev ui.
+
+1. For 1st run, allow popup for localhost in Chrome.
+
+1. Configure your `.env` file to add two more variables before running the agent:
+
+  * OAUTH_CLIENT_ID={your client id}
+  * OAUTH_CLIENT_SECRET={your client secret}
+
+  Note: don't create a separate .env, instead put it to the same .env file that
+  stores your Vertex AI or Dev ML credentials
+
+1. Set `RUN_WITH_ADC=False` in `agent.py` and run the agent
+
+## Sample prompts
+
+* which weather datasets exist in bigquery public data?
+* tell me more about noaa_lightning
+* which tables exist in the ml_datasets dataset?
+* show more details about the penguins table
+* compute penguins population per island.