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/insight.py
import json
from functools import lru_cache
from typing import Any, Dict, Optional, Type
import structlog
from django.db.models import Count, OuterRef, QuerySet, Subquery
from django.db.models.query_utils import Q
from django.http import HttpResponse
from django.utils.text import slugify
from django.utils.timezone import now
from django_filters.rest_framework import DjangoFilterBackend
from drf_spectacular.utils import OpenApiResponse
from rest_framework import exceptions, request, serializers, status, viewsets
from rest_framework.decorators import action
from rest_framework.permissions import IsAuthenticated