Add errorlist and sqlstate to mysqli_stmt

Summary: - This adds error_list and sqlstate properties on mysqli_stmt. Mostly copied from the same properties on mysqli

Fixes #3048

Reviewed By: @JoelMarcey

Differential Revision: D1407664
Fix crash on misuse of FormatString (and other newtypes?)

Summary: Once again, we should be adding an error instead of asserting
something.

Reviewed By: @gabelevi

Differential Revision: D1428946