`INTERVAL '1 hour'` should be equivalent to `INTERVAL 1 HOUR`

**Use case**
People are used to Postgres.
{
    ParserKeyword columns("COLUMNS");
    ParserList columns_p(std::make_unique<ParserCompoundIdentifier>(), std::make_unique<ParserToken>(TokenType::Comma), false);
    ParserStringLiteral regex;
    if (!columns.ignore(pos, expected))
        return false;
    if (pos->type != TokenType::OpeningRoundBracket)
        return false;
    ++pos;
    ASTPtr column_list;
    ASTPtr regex_node;
    if (!columns_p.parse(pos, column_list, expected) && !regex.parse(pos, regex_node, expected))
        return false;
    if (pos->type != TokenType::ClosingRoundBracket)
        return false;
    ++pos;
    auto res = std::make_shared<ASTColumnsMatcher>();
    if (column_list)
    {
        res->column_list = column_list;
        res->children.push_back(res->column_list);
    }
    else
    {
        res->setPattern(regex_node->as<ASTLiteral &>().value.get<String>());
        res->children.push_back(regex_node);
    }
    ParserColumnsTransformers transformers_p;
    ASTPtr transformer;