## Is your feature request related to a problem?

When setting up dashboards I'd like to filter the stats to a certain page/subdomain. 

## Describe the solution you'd like

Allow adding a extra filters for all graphs on a dashboard (e.g. filter by $current_url)

## Describe alternatives you've considered

Updating every graph in dashboard one-by-one and then reverting them back.

## Additional context

Related to https://github.com/PostHog/posthog/issues/780

Datadog has a decent solution for this: https://docs.datadoghq.com/dashboards/template_variables/, which I think we can simplify and use ourselves.

Came up during #2560 

#### *Thank you* for your feature request – we love each and every one!

posthog/api/test/test_insight.py
dashboard_own_team: Dashboard = Dashboard.objects.create(team=self.team)
        another_team = Team.objects.create(organization=self.organization)
        dashboard_other_team: Dashboard = Dashboard.objects.create(team=another_team)
        self._create_insight(
            data={
                "filters": {
                    "events": [{"id": "$pageview"}],
                    "properties": [{"key": "$browser", "value": "Mac OS X"}],
                    "date_from": "-90d",
                },
                "dashboards": [dashboard_own_team.pk, dashboard_other_team.pk],
            },
            expected_status=status.HTTP_400_BAD_REQUEST,
        )
    def test_cannot_update_insight_with_dashboard_from_another_team(self):