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

**Use case**
People are used to Postgres.
{
    ParserIdentifier non_parametric;
    ParserIdentifierWithParameters parametric;
    if (parametric.parse(pos, node, expected))
        return true;
    ASTPtr ident;
    if (non_parametric.parse(pos, ident, expected))
    {
        auto func = std::make_shared<ASTFunction>();
        tryGetIdentifierNameInto(ident, func->name);
        node = func;
        return true;
    }
    return false;
}
}