When exporting data from [an insight](https://app.posthog.com/insights/oVHjTLUD), the action names weren't exported, making the CSV a little hard to follow.

As a user, I'd expect to see the same data in the export as I see in the table in-app.

<img width="1012" alt="image" src="https://user-images.githubusercontent.com/154479/166958828-9b3add76-633b-4f1d-ad2b-cf1ea2888b95.png">

posthog/api/test/test_insight.py
response_nonexistent_property = self.client.get(
            f"/api/projects/{self.team.id}/insights/trend/?events={json.dumps([{'id': '$pageview'}])}&properties={json.dumps([{'type':'event','key':'foo','value':'barabarab'}])}"
        )
        response_nonexistent_cohort = self.client.get(
            f"/api/projects/{self.team.id}/insights/trend/?events={json.dumps([{'id': '$pageview'}])}&properties={json.dumps([{'type':'cohort','key':'id','value':2137}])}"
        )  
        response_nonexistent_property_data = response_nonexistent_property.json()
        response_nonexistent_cohort_data = response_nonexistent_cohort.json()
        response_nonexistent_property_data.pop("last_refresh")
        response_nonexistent_cohort_data.pop("last_refresh")
        self.assertEntityResponseEqual(
            response_nonexistent_property_data["result"], response_nonexistent_cohort_data["result"]
        )  
    def test_cohort_without_match_group_works(self):
        whatever_cohort_without_match_groups = Cohort.objects.create(team=self.team)
        response_nonexistent_property = self.client.get(
            f"/api/projects/{self.team.id}/insights/trend/?events={json.dumps([{'id': '$pageview'}])}&properties={json.dumps([{'type':'event','key':'foo','value':'barabarab'}])}"
        )
        response_cohort_without_match_groups = self.client.get(
            f"/api/projects/{self.team.id}/insights/trend/?events={json.dumps([{'id':'$pageview'}])}&properties={json.dumps([{'type':'cohort','key':'id','value':whatever_cohort_without_match_groups.pk}])}"
        )  
        self.assertEqual(response_nonexistent_property.status_code, 200)
        response_nonexistent_property_data = response_nonexistent_property.json()
        response_cohort_without_match_groups_data = response_cohort_without_match_groups.json()
        response_nonexistent_property_data.pop("last_refresh")
        response_cohort_without_match_groups_data.pop("last_refresh")
        self.assertEntityResponseEqual(
            response_nonexistent_property_data["result"], response_cohort_without_match_groups_data["result"]
        )  
    def test_precalculated_cohort_works(self):