Discovery API:bigquery.v2

Iceberg timestamp autodetection and UDF clarifications

The timestampTargetPrecision field within ExternalDataConfiguration and JobConfigurationLoad now explicitly supports Iceberg External Tables, joining CSV, Parquet, and Avro. This allows developers to control how timestamp precision (e.g., 6 or 12 digits) is handled during autodetection for Iceberg sources. Additionally, the description for containerRequestConcurrency in ExternalRuntimeOptions has been updated to clarify that it specifically governs Python UDF container instances.