Add RLS support and fix permission checks (#2309)

- Previously, age only set ACL_SELECT and ACL_INSERT in RTEPermissionInfo,
  bypassing pg's privilege checking for DELETE and UPDATE operations.
- Additionally, RLS policies were not enforced because AGE uses CMD_SELECT
  for all Cypher queries, causing the rewriter to skip RLS policy application.

Permission fixes:
- Add ACL_DELETE permission flag for DELETE clause operations
- Add ACL_UPDATE permission flag for SET/REMOVE clause operations
- Recursively search RTEs including subqueries for permission info

RLS support:
- Implemented at executor level because age transforms all cypher
  queries to CMD_SELECT, so pg's rewriter never adds RLS
  policies for INSERT/UPDATE/DELETE operations. There isnt an
  appropriate rewriter hook to modify this behavior, so we do it
  in executor instead.
- Add setup_wcos() to apply WITH CHECK policies at execution time
  for CREATE, SET, and MERGE operations
- Add setup_security_quals() and check_security_quals() to apply
  USING policies for UPDATE and DELETE operations
- USING policies silently filter rows (matching pg behavior)
- WITH CHECK policies raise errors on violation
- DETACH DELETE raises error if edge RLS blocks deletion to prevent
  dangling edges
- Add permission checks and rls in startnode/endnode functions
- Add regression tests

Assisted-by AI

Resolved Conflicts:
	src/backend/executor/cypher_create.c
	src/backend/executor/cypher_delete.c
	src/backend/executor/cypher_merge.c
	src/backend/executor/cypher_set.c
	src/backend/executor/cypher_utils.c

Author: MuhammadTahaNaveed

Makefile

@@ -112,7 +112,8 @@ REGRESS = scan \
           jsonb_operators \
           list_comprehension \
           map_projection \
-          direct_field_access
+          direct_field_access \
+          security
 
 ifneq ($(EXTRA_TESTS),)
   REGRESS += $(EXTRA_TESTS)