feat(expr): allow explicit cast serial to bigint

[TennyZhuang]

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What's changed and what's your intention?

#15008

We only allow an explicit casting in the PR, we can extend the behavior later, but we need that for testing.

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[ramoncjs3]

I've currently updated to the latest version v2.0.1 and I still can't get a self-incrementing ID column, I need your help, thanks.

As you can see above, I have converted the _row_id column display to a bigint type, but for some reason the id column is still empty.