ref #9436
Currently EPHEMERAL column requires an explicit default value provided on CREATE TABLE - we can allow implicit default there

if (default_expression)
    {
        column_declaration->default_specifier = default_specifier;
        column_declaration->default_expression = default_expression;
        column_declaration->children.push_back(std::move(default_expression));
    }
    if (comment_expression)
    {
        column_declaration->comment = comment_expression;
        column_declaration->children.push_back(std::move(comment_expression));
    }
    if (codec_expression)
    {
        column_declaration->codec = codec_expression;
        column_declaration->children.push_back(std::move(codec_expression));
    }
    if (ttl_expression)
    {
        column_declaration->ttl = ttl_expression;
        column_declaration->children.push_back(std::move(ttl_expression));
    }
    return true;
}
class ParserColumnDeclarationList : public IParserBase
{
protected:
    const char * getName() const override { return "column declaration list"; }
    bool parseImpl(Pos & pos, ASTPtr & node, Expected & expected) override;
};
class ParserIndexDeclaration : public IParserBase