`Expr::is_volatile` ignores the volatility of aggregate, window and higher-order functions

[neilconway]

Describe the bug

Expr::is_volatile_node only checks Expr::ScalarFunction. AggregateUDF, WindowUDF and HigherOrderUDF declare a volatility too, but Expr::is_volatile never sees it, so optimizer rules that rely on it (CSE, filter pushdown, the simplifier, …) treat volatile user-defined functions of those kinds as deterministic. The physical layer already checks HOF volatility in HigherOrderFunctionExpr::is_volatile_node; the logical Expr is the outlier.

To Reproduce

No response

Expected behavior

No response

Additional context

All built-in functions in these categories are Immutable, so only user-defined functions are affected.

[neilconway]

@1fanwang @anishmehta24 Thanks for sending PRs for this issue. In the future, please try to self-assign a ticket (via take) before working on it to avoid duplicate work.

[anishmehta24]

Understood, and sorry for the noise: I have closed #25513 in favour of #25511, which was first. I will take before starting next time.

[1fanwang]

Understood. I'll use take and confirm assignment before starting work next time.