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
filter = Filter(request=request, team=self.team)
        next = (
            format_paginated_url(request, filter.offset, BREAKDOWN_VALUES_LIMIT)
            if len(result["result"]) >= BREAKDOWN_VALUES_LIMIT
            else None
        )
        if self.request.accepted_renderer.format == "csv":
            csvexport = []
            for item in result["result"]:
                line = {"series": item["label"]}
                for index, data in enumerate(item["data"]):
                    line[item["labels"][index]] = data
                csvexport.append(line)
            renderer = csvrenderers.CSVRenderer()
            renderer.header = csvexport[0].keys()
            export = renderer.render(csvexport)
            if request.GET.get("export_insight_id"):
                export = "{}/insights/{}/\n".format(SITE_URL, request.GET["export_insight_id"]).encode() + export
            response = HttpResponse(export)
            response[
                "Content-Disposition"
            ] = 'attachment; filename="{name} ({date_from} {date_to}) from PostHog.csv"'.format(
                name=slugify(request.GET.get("export_name", "export")),
                date_from=filter.date_from.strftime("%Y-%m-%d -") if filter.date_from else "up until",
                date_to=filter.date_to.strftime("%Y-%m-%d"),
            )
            return response
        return Response({**result, "next": next})
    @cached_function
    def calculate_trends(self, request: request.Request) -> Dict[str, Any]: