[release-12.1] Quote EXTRACT fields in PG14-16 ruleutils

[ibrahim halatci (ihalatci)]

Summary

Backport the focused EXTRACT identifier quoting parity fix from #8804 to release-12.1 for PostgreSQL 14, 15, and 16.

• quote EXTRACT field identifiers in the copied PG14/PG15/PG16 ruleutils implementations
• add one shared, repeat-safe extract_deparse regression covering every supported PostgreSQL major
• run it from release-12's existing current-library multi_1_schedule; this branch predates the N-1 mixed-library schedule split
• preserve the existing shard-aware Citus deparser changes

Fixes #8803.

Main PR: #8804

Validation

• -Werror builds against PostgreSQL 14.24, 15.19, and 16.15
• shared extract_deparse regression: 8/8 repetitions on each supported PostgreSQL major
• expected output generated with the release-12 regression runner
• shared SQL matches the main-branch test byte-for-byte; expected output matches the proven release runner output
• relevant style, schedule, SQL snapshot, and diff checks

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.64%. Comparing base (377c1f2) to head (956a13f).
⚠️ Report is 17 commits behind head on release-12.1.

Additional details and impacted files

@@               Coverage Diff                @@
##           release-12.1    #8813      +/-   ##
================================================
- Coverage         89.65%   89.64%   -0.01%     
================================================
  Files               276      276              
  Lines             59790    59940     +150     
  Branches           7471     7494      +23     
================================================
+ Hits              53605    53735     +130     
- Misses             4041     4052      +11     
- Partials           2144     2153       +9     

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