Fix comparison between tuples with nullable elements

Fix comparison between tuples with nullable elements inside and strings. As an example, before the change comparison between a Tuple (1, null) and a String '(1,null)' would result in an error. Another example would be a comparison between a Tuple (1, a), where a is a Nullable column, and a String '(1, 2)'. This change addresses these issues. #77323 (Alexey Katsman).