Fix replace_property_refs() ignoring the root of expression tree

Fix replace_property_refs() ignoring the root of expression tree

replace_property_refs() called expression_tree_mutator() with the root
of the expression tree as the input node.  But
expression_tree_mutator() does not call the mutator function on the
root node, so the root node remains unchanged.  If the root node is a
property reference or a lateral reference -- the two node kinds that
replace_property_refs_mutator() rewrites -- it is returned unchanged.
Modules after the rewriter do not know about property reference nodes,
resulting in "ERROR: unrecognized node type: 63".  Since varlevelsup
of lateral references is not incremented, they are not resolved
correctly in the planner, leading to many different symptoms.  Fix
this by calling replace_property_refs_mutator() directly from
replace_property_refs(), similar to how other mutator functions do.

The only case when a property reference or a lateral reference can be
the root of a GRAPH_TABLE expression tree is when it is a bare
property reference or a bare lateral reference in the WHERE clause.
The COLUMNS clause is passed to replace_property_refs() as a
targetlist.  Every other expression has at least one expression node
covering the property reference or a lateral reference in the
expression tree.  That explains why this bug was not seen so far.

Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reported-by: Noah Misch <noah@leadboat.com>
Discussion: https://www.postgresql.org/message-id/flat/20260630173053.51.noahmisch%40microsoft.com