Support Redshift materialized view BACKUP clauses

[minleejae]

Fixes #1735

Changes

• Support BACKUP YES and BACKUP NO after a Redshift materialized view name, including combinations with AUTO REFRESH.
• Store the explicit choice as a nullable Boolean so an omitted BACKUP clause remains omitted when rendering.
• Share materialization-option rendering between CreateView and CreateViewDeParser.
• Reject malformed, duplicated, or misordered BACKUP clauses and BACKUP on ordinary views, without making BACKUP a globally reserved identifier.

This is deliberately scoped to BACKUP. It does not add Redshift distribution or sort-key clauses.

Verification

• Full Gradle check (tests, Checkstyle, PMD, Spotless).
• Maven clean verify with Java 17.
• Round-trip, AST mutation, invalid syntax, AUTO REFRESH, and table-discovery regression tests.

Reference: Amazon Redshift CREATE MATERIALIZED VIEW.