feat(sqlsmith): support generation of select * except

[cardigan1008]

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What's changed and what's your intention?

This PR adds support for SELECT * EXCEPT (...) in SQLSmith.

Previously, we avoided generating SELECT * queries due to the risk of implicitly including system-generated columns (e.g., window_start from tumble/hop functions), which could lead to binding errors.

Now, with a stricter generation policy that restricts tumble/hop to only operate on base tables, such implicit columns are no longer propagated. As a result, SELECT * and SELECT * EXCEPT (...) can be safely generated. The implementation randomly excludes a subset of columns from the current schema to construct a valid EXCEPT list.

Checklist

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Release note