V2 new filter, aggregation

[Idokah]

Didn't change e2e yet.
Changed filter_parser to work with v2 API

The filter was :

filter: 
{
  operator: '$eq'
  fieldName: 'field'
  value: 'val'
}

filter changed to:

filter:
{
  field:  { $eq: 'val' }
}

aggregation was:

filter: { somefilter },
aggregation: {
    processingStep: {
        _id: {
            field1: 'field',
        },
        myAvg: {
            $avg: 'somefield'
        }
    },
    postFilteringStep: {
        somefilter
    },
}

aggregation changed to:

filter: { somefilter},
processingStep: {
    _id: {
        field1: '$field',
    },
    myAvg: {
        $avg: `$somefield`
    }
},
postFilteringStep: {
    somefilter
},

As you can see, in aggregation:
there's no aggregation object.
The fields are with $ prefix.

[noam-almog]

let's update the PR and explain in high level what changed in the API
filter was .... changed to ...
i can't really understand what you are trying to commit like this.

[Idokah]

let's update the PR and explain in high level what changed in the API filter was .... changed to ... i can't really understand what you are trying to commit like this.
@noam-almog done