refactor: replace parentNodeTypes usage with DeparserContext.spawn() method

- Replace parentNodeTypes=[] with new DeparserContext()
- Replace parentNodeTypes=[...context.parentNodeTypes, nodeType] with context.spawn(nodeType)
- Replace {...context, property: true} patterns with context.spawn(methodName, {property: true})
- Fix context propagation issues in IndexElem and CopyStmt methods
- Ensure proper context spawning for GIN index parameters and COPY statement WITH clauses
- All 279 test suites continue to pass with the new context system

Co-Authored-By: Dan Lynch <[email protected]>

Author: devin-ai-integration[bot]