Allow cross joins in the Query Builder with multiple join keys

**Is your feature request related to a problem? Please describe.**
As a user, I want to build queries featuring cross joins.

For example, suppose I have a list of actions per company, and I want to sum them up per day, and **include zeroes** the only way to do this properly is by using a date spine (unless I'm mistaken ?)

```sql
select
company_name,
week,
count(*),
from date_spine_week
cross join companies as company
left join actions as action on action.date_week = date_spine_week.week
and company.name = action.company_name
group by week, company_name
```

**Describe the solution you'd like**
A way to select cross join in the query builder, and the ability to pick one join key for each cross joined item

**Describe alternatives you've considered**
SQL Query. It actually works, but then we are losing the "automatic filters" that you can get on dashboards

**How important is this feature to you?**
It would make life much easier when computing periodic stats, when we need to include zeroes systematically

**Additional context**
Example of displayed visualization using a graph


No files or tests are named in the issue. Start by tracing the Query Builder entry point for join configuration and compare it with the SQL cross-join example; done means the builder supports cross joins with multiple join keys while preserving dashboard automatic filters.

Written by the indexing model from the issue text.