Improve `SQLAlchemy` `ColumnElement` serialization for hashing

[ilongin]

Currently we have function serialize_column_element() which takes one instance of ColumnElement and returns deterministic hashable structure in form of dict.
The issue is that we have couple of most common variations of ColumnElement checked like BinaryExpression but there might be more so we should refactor it to work for any kind of ColumnElement without explicit checks for subclasses.