Populate snapshot summary in iceberg ConnectorOutputMetadata

[raunaqmorarka]

Description

Adds useful information to TableFinish operator summary of CTAS, INSERT and REFRESH MV queries
e.g.

"connectorOutputMetadata" : {
  "trino_query_id" : "20260120_051928_00000_uh66u",
  "trino_user" : "raunaq.morarka",
  "added-data-files" : "5",
  "added-records" : "25",
  "added-files-size" : "5577",
  "changed-partition-count" : "5",
  "total-records" : "25",
  "total-files-size" : "5577",
  "total-data-files" : "5",
  "total-delete-files" : "0",
  "total-position-deletes" : "0",
  "total-equality-deletes" : "0",
  "engine-version" : "dev",
  "engine-name" : "trino",
  "iceberg-version" : "Apache Iceberg 1.10.1 (commit ccb8bc435062171e64bc8b7e5f56e6aed9c5b934)"
}

Additional context and related issues

Release notes

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## Section
* Fix some things. ({issue}`issuenumber`)

[Copilot]

Pull request overview

This PR enhances Iceberg table operations by populating snapshot summary metadata in ConnectorOutputMetadata for CTAS, INSERT, and REFRESH MATERIALIZED VIEW queries. The metadata includes useful metrics like added records, data files, file sizes, and partition counts that are now visible in the TableFinish operator summary.

Changes:

• Created new IcebergCommitMetadata class to wrap Iceberg snapshot summary information
• Modified finishInsert to return snapshot summary instead of file paths
• Modified finishRefreshMaterializedView to return snapshot summary instead of file paths
• Added test coverage for INSERT, CTAS, and REFRESH MV operations

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 6 comments.

File	Description
IcebergCommitMetadata.java	New class implementing ConnectorOutputMetadata to hold snapshot summary metrics
IcebergMetadata.java	Modified finishInsert and finishRefreshMaterializedView to capture and return snapshot summaries; removed HiveWrittenPartitions dependency
BaseIcebergConnectorTest.java	Added testCommitMetrics to verify snapshot metadata is properly populated for INSERT, CTAS, and REFRESH MV operations

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