feat: Add iceberg connector + Tests + Docs

[royendo]

Adds Apache Iceberg as a new connector, leveraging DuckDB's native Iceberg support. Tested with local filesystem and GCS catalogs.

Backend:

• Register `iceberg` as a DuckDB source connector in `runtime/drivers/duckdb/duckdb.go`
• Add Iceberg connector schema to `runtime/parser/schema/project.schema.yaml` with catalog type, storage type, and credential properties

Frontend:

• Multi-step form schema (`iceberg.ts`) for configuring Iceberg connections (catalog URI, storage type, credentials)
• Apache Iceberg logo SVG icons and connector icon mapping
• Dynamic field rendering in `JSONSchemaFormRenderer` and `GroupedFieldsRenderer` for grouped/conditional form fields
• GCS and Azure Blob Storage icon components

Documentation:

• User guide at `docs/developers/build/connectors/data-source/iceberg.md`
• Reference docs for Iceberg connector YAML properties

Integration tests:

• Resolver test (`connector_iceberg.yaml`) validating Iceberg → DuckDB materialization with TPC-H lineitem data (51,793 rows, 16 columns)

Checklist:

• Covered by tests
• Ran it and it works as intended
• Reviewed the diff before requesting a review
• Checked for unhandled edge cases
• Linked the issues it closes
• Checked if the docs need to be updated. If so, create a separate Linear DOCS issue
• Intend to cherry-pick into the release branch
• I'm proud of this work!

[royendo]

Make changes:

Tab 1: Direct Table Path
• Storage dropdown
• Storage connector
• Table path input
• Done

Tab 2: Managed Table (Catalog)
• Catalog dropdown (REST, PG, MySQL)
• Catalog connector
• Storage dropdown
• Storage connector
• Table identifier input (db.table)
• Done

[NamanMahor]

rill support google json credendtial but duckdb only support hmac so I think iceberg_scan only support hmac too. May be better to mention here.