Ability to use filters on 'reverse' queries

[t-persson]

Description

Currently we allow a 'reverse' query on each event in the API.
These 'reverse' queries provide us with the ability to find which events link to this one.
The queries are very dumb and will always fetch every single event that links to the current event, even though we don't want them. This puts an extreme load on the mongodb server, slows down response time and gives us a lot of unnecessary information.

Motivation

Effectiveness in our queries and filtering is a key feature of graphql APIs.

Exemplification

Imagine that we have 1 EnvironmentDefined and 1 ConfidenceLevelModified linked to a testSuiteStarted.
By 'reverse' querying for 'EnvironmentDefined' we will also, every single time, query for the ConfidenceLevelModified. Event if we don't specify that want to search for it.
Imagine now that we have 1000 links.

{
  testSuiteStarted(last: 1) {
    edges {
      node {
        reverse {
          edges {
            node {
              ... on EnvironmentDefined {
                data {
                  name
                }
              }
            }
          }
        }
      }
    }
  }
}

Benefits

Faster response times, less CPU usage

Possible Drawbacks

None