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

**Use case**
People are used to Postgres.
ParserIdentifier ident_p;
        auto parse_id = [&]
        {
            ASTPtr expr;
            if (!element_p.parse(pos, expr, expected))
                return false;
            if (!as.ignore(pos, expected))
                return false;
            ASTPtr ident;
            if (!ident_p.parse(pos, ident, expected))
                return false;
            auto replacement = std::make_shared<ASTColumnsReplaceTransformer::Replacement>();
            replacement->name = getIdentifierName(ident);
            replacement->expr = std::move(expr);
            replacements.emplace_back(std::move(replacement));
            return true;
        };
        if (!ParserList::parseUtil(pos, expected, parse_id, false))
            return false;
        if (pos->type != TokenType::ClosingRoundBracket)
            return false;
        ++pos;
        auto res = std::make_shared<ASTColumnsReplaceTransformer>();
        res->children = std::move(replacements);
        node = std::move(res);
        return true;
    }
    return false;
}
bool ParserAsterisk::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)