Filter pushdown issue with aggregating inline views and CTE's

Filters are applied to the outer SELECT. This cannot work with aggregating inline views and CTE's (common table expressions if dimensionality is reduced. With `FILTER_PARAMS` we can push down the filter inside the inline view or CTS like this:

Having this simple example with a transaction table:
```
CREATE TABLE food_sales (
CREATED_TS timestamp PRIMARY KEY,
ITEM string,
AMOUNT integer
);
```
and a Cube defined for aggregating top-5 with all others (typical pie chart) we want to filter for `AMOUNT < n` (eg. finding top-5 items in a lower segment):

```
cube(`FoodSales_Aggr_Top5`, {
sql: `WITH top5 AS (
SELECT ITEM, sum(AMOUNT) AS AMOUNT_SUM
FROM food_sales
WHERE ${FILTER_PARAMS.FoodSales_Aggr_Top5.amount.filter('AMOUNT')}
GROUP BY ITEM
ORDER BY AMOUNT_SUM DESC
LIMIT 5
)
SELECT * FROM top5
UNION ALL
SELECT 'Others' as ITEM, sum(AMOUNT) AS AMOUNT_SUM
FROM food_sales
WHERE ${FILTER_PARAMS.FoodSales_Aggr_Top5.amount.filter('AMOUNT')}
AND ITEM NOT IN (SELECT ITEM FROM top5)`,
dataSource: `default`,

title: `Food Sales Top 5`,
description: `Food Sales aggregated Top5 sales`,

dimensions: {
created: {
sql: 'CREATED_TS',
type: 'time',
primaryKey: true,
shown: false
},
item: {
sql: `ITEM`,
type: `string`,
},
amount: {
sql: `AMOUNT`,
type: `number`,
shown: false
}
},

measures: {
sumAmount: {
sql: `AMOUNT_SUM`,
type: `sum`
}

}
});

```

Now we define this query with the filter `AMOUNT < 1000`:
```
{
measures: [
'FoodSales_Aggr_Top5.sumAmount'
],
dimensions: [
'FoodSales_Aggr_Top5.item'
],
filters: [{
member: 'FoodSales_Aggr_Top5.amount',
operator: 'lt',
values: ['1000']
}]
}
```

This is the generated SQL:
```
SELECT "food_sales__aggr__top5".ITEM "food_sales__aggr__top5__item",
sum("food_sales__aggr__top5".AMOUNT_SUM) "food_sales__aggr__top5__sum_amount"
FROM (
WITH top5 AS (
SELECT ITEM,
sum(AMOUNT) AS AMOUNT_SUM
FROM food_sales
WHERE AMOUNT < ?
GROUP BY ITEM
ORDER BY AMOUNT_SUM DESC
LIMIT 5)
SELECT * FROM top5
UNION ALL
SELECT 'Others' as ITEM,
sum(AMOUNT) AS AMOUNT_SUM
FROM food_sales
WHERE AMOUNT < ? AND ITEM NOT IN (SELECT ITEM FROM top5)
) AS "food_sales__aggr__top5"
WHERE ("food_sales__aggr__top5".AMOUNT < ?)
GROUP BY 1
ORDER BY 2 DESC
```

As we see we have an additional `WHERE` clause on the outer `SELECT` where we do not have the `AMOUNT` field because of aggregation.

My expectation is that this is not needed here because we have explicitly used `FILTER_PARAMS` for this field inside the SQL. Also, I would expect the field `AMOUNT` would not appear in the outer SELECT since I set `shown: false` in the Cube definition.

Maybe there is already a solution to such kind of queries and I haven't found it yet?