Support secondary ART indexes

[adsharma]

Summary

• allow ART indexes on non-primary node properties
• store duplicate offsets in secondary ART leaves and maintain them across insert, update, delete, checkpoint, and reload
• use secondary ART indexes for simple single-table equality predicates

Validation

• ninja -C build/release test/runner/e2e_test
• E2E_TEST_FILES_DIRECTORY=test/test_files build/release/test/runner/e2e_test --gtest_filter="ddl_empty"
• manual EXPLAIN check confirmed PRIMARY_KEY_SCAN_NODE_TABLE with Index: ART for a secondary name lookup