Fix the order of parameters listed by DESCRIBE INPUT

[kasiafi]

Before this change, if a prepared query contained a CTE,
the parameters from the CTE were listed last by DESCRIBE
INPUT, preceded by all parameters from the enclosing query.
It was incorrect, since CTE is first in the query text.

This fix changes the order in which the CTE and the enclosing
query body are visited in the AST builder, thus changing the
order of parameters in the DESCRIBE INPUT result.

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# General
* Fix the order of parameters listed by DESCRIBE INPUT for certain prepared queries containing a WITH clause.

[martint]

How does it relate to #14914 ?

[kasiafi]

How does it relate to #14914 ?

Oh, I missed that PR, and the issue. I was addressing the same problem. My approach was easier and less general though.
Closing this PR.