Add an agent template adk_bigquery_base

[shobsi]

Would it make sense to have an agent template adk_bigquery_base in addition to adk_base, to give a (mostly) ready agent to be deployed, to accelerate agentic analytics powered by BigQuery? Technically one could start from adk_base and then modify the agent code to update agent instruction and tools to gear to BigQuery usage, but the proposal shortens that journey.

@elia-secchi

[eliasecchig]

As mentioned over chat, the best place to do that would be google/adk-samples !