Support Iceberg SQL views #1099

Add support for persisted Iceberg SQL views so C++ applications can create, inspect, and manage view definitions through a REST catalog.

The initial metadata types and validation are under review in #1069. This issue tracks the complete implementation and expands the view-related work listed in #273.

Proposed scope

• View metadata types, version history, representations, and validation — feat(view): add view metadata types and validation #1069.
• View metadata JSON parsing and serialization, including preservation of unknown representation payloads.
• View update and requirement types matching the REST wire contract.
• A metadata builder for schema/version reuse, ordered updates, history retention, and dialect-removal checks.
• A separate ViewCatalog interface and View handle, with an in-memory implementation for lifecycle tests.
• REST read operations: load, exists, and paginated list.
• REST mutations: create, replace, rename, drop, and register, plus property and location updates.

Expected behavior

• Existing table catalog APIs remain compatible.
• View handles expose immutable metadata snapshots. Refresh checks the view UUID and installs metadata and response configuration together.
• SQL representation lookup matches dialects without regard to ASCII case and reports an absent dialect.
• REST operations honor advertised endpoints and reuse existing authentication and error-handling behavior.
• Mutations preserve ordered update semantics and report uncertain commit outcomes without automatically replaying the commit.

Validation

• Metadata and JSON tests using view-format fixtures from the Java and Rust implementations.
• In-memory lifecycle tests covering history, rollback, schema/version reuse, refresh, and snapshot immutability.
• REST tests for request/response handling, endpoint discovery, pagination, conflicts, and uncertain commit outcomes.
• A reference REST catalog integration test covering create, load, replace, rename, and drop.

SQL parsing and planning, materialized views, production storage in non-REST backends, and conditional replacement beyond the standard REST requirements are outside this initial scope.

References:

• Iceberg view specification
• Iceberg REST catalog specification
• Initial implementation: feat(view): add view metadata types and validation #1069