feat(expr): allow partial option arguments in functions

[wangrunji0408]

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What's changed and what's your intention?

Currently #[function] only accepts all arguments as Option or none of them as Option. This PR breaks this limitation, allowing partial Option arguments.

For example:

#[function("array_remove(anyarray, any) -> anyarray")]
fn array_remove(array: ListRef<'_>, elem: Option<ScalarRefImpl<'_>>) -> ListValue {...}

which will be called when elem is null, but not when array is null.

Checklist

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