Add user-agent in GCSFileIO to identify Iceberg traffic on GCS

[breach10ck]

Feature Request / Improvement

Currently the user-agent for traffic from GCSFileIO to GCS is unknown, having an user-agent will help in analyzing and prioritizing the performance improvements for Iceberg FileIO integration with GCS.

To do this, we'll need to add the configurations in StorageOptions : https://github.com/apache/iceberg/blob/main/gcp/src/main/java/org/apache/iceberg/gcp/gcs/PrefixedStorage.java#L52

Query engine

None

Willingness to contribute

• I can contribute this improvement/feature independently
• I would be willing to contribute this improvement/feature with guidance from the Iceberg community
• I cannot contribute this improvement/feature at this time