[release-14.0] Quote EXTRACT fields in PG16-18 ruleutils

[ibrahim halatci (ihalatci)]

Summary

Backport the focused EXTRACT identifier quoting parity fix from #8804 to release-14.0 for PostgreSQL 16, 17, and 18.

• quote EXTRACT field identifiers in the copied PG16/PG17/PG18 ruleutils implementations
• add one shared, repeat-safe extract_deparse regression covering every supported PostgreSQL major
• keep that new-binary assertion in multi_1_create_citus_schedule, outside the 14.2 N-1 mixed-library matrix
• preserve the existing shard-aware Citus deparser changes

Fixes #8803.

Main PR: #8804

Validation

• built against PostgreSQL 16.15, 17.11, and 18.6 in isolated WSL prefixes
• pre-consolidation PG16/PG17/PG18 focused tests passed eight repetitions with whole schedule lines
• final shared extract_deparse test passed focused PG16 validation; identical shared SQL/expected output is scheduled for PG16-18
• PG16 and PG18 full owning schedules passed 39/39 before consolidation
• PG17 full schedule was 188/190; both failures reproduced unchanged on pristine release-14.0 and did not touch EXTRACT output
• Citus formatting/style checks, SQL snapshots, and git diff --check passed
• follow-up isolates the new assertion from expected pre-fix 14.2 coordinator-library behavior in N-1 CI

CI triage

All current-version, feature, packaging, style, snapshot, and relevant N-1 checks pass. The remaining Test Citus Lib N-1 / PG18 - check-multi failure and all 32 Test flakyness failures match unmodified release-14.0 baseline run https://github.com/citusdata/citus/actions/runs/32951765361. The N-1 failure is unrelated multi_insert_select AIO DEBUG output; the flakiness gate runs broad release-vs-main history and fails pre-existing tests. codecov/project is downstream of those baseline failures.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.54%. Comparing base (c457188) to head (0e08c23).

Additional details and impacted files

@@               Coverage Diff                @@
##           release-14.0    #8809      +/-   ##
================================================
- Coverage         88.57%   88.54%   -0.03%     
================================================
  Files               289      289              
  Lines             64585    64584       -1     
  Branches           8121     8120       -1     
================================================
- Hits              57208    57189      -19     
- Misses             5028     5049      +21     
+ Partials           2349     2346       -3     

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.