## Bug description

Support refreshing all dashboard items. This feature was temporarily removed because it wasn't working properly)

## Expected behavior
- All dashboard items should be properly refreshed and the `items` object in the `dashboardLogic` should contain the latest information.
- From user feedback. I expect items to be automatically refreshed every hour or so (e.g. if I'm a marketer that looks at graphs continuously during the day, or have a screen dedicated just to metrics).


## How to reproduce

1. Create a dashboard with multiple items
2. Attempt to refresh all and check the last refresh timestamp for each item (remember to uncomment relevant code)

## Environment

- [X] PostHog Cloud
- [X] self-hosted PostHog, version/commit: _please provide_

## Additional context
Follow-up to #3363

## Technical context

When refreshing all dashboard items (via `refreshAllDashboardItems()`) not all items are consistently refreshed all the time. Tested for instance with a dashboard with a couple of mixed (different type) graphs. Some items are still kept on "last refreshed 10 minutes ago".

In addition to the above, as originally reported on #3608, when calling `refreshAllDashboardItems` we update each item in their own scope, which means that the general `items` object in the upper scope logic (`dashboardLogic.js`) doesn't get updated. Not sure if we should propagate the change upwards, re-fetch everything, or just do a general refresh.

The UX problem this is causing is that the "Last refreshed" label now introduced in the dashboards gets outdated because `items` doesn't get updated. Having this object with outdated information also leads to other confusing UX issues.


#### *Thank you* for your bug report – we love squashing them!

posthog/api/test/test_dashboard.py
dashboard = Dashboard.objects.create(
            team=self.team, name="private dashboard", created_by=self.user, creation_mode="template",
        )
        response = self.client.patch(
            f"/api/dashboard/{dashboard.id}",
            {
                "name": "dashboard new name",
                "creation_mode": "duplicate",
                "tags": ["official", "engineering"],
                "description": "Internal system metrics.",
            },
        )
        self.assertEqual(response.status_code, status.HTTP_200_OK)
        response_data = response.json()
        self.assertEqual(response_data["name"], "dashboard new name")
        self.assertEqual(response_data["created_by"]["distinct_id"], self.user.distinct_id)
        self.assertEqual(response_data["creation_mode"], "template")
        self.assertEqual(response_data["description"], "Internal system metrics.")
        self.assertEqual(response_data["tags"], ["official", "engineering"])
        dashboard.refresh_from_db()
        self.assertEqual(dashboard.name, "dashboard new name")
        self.assertEqual(dashboard.tags, ["official", "engineering"])
    def test_create_dashboard_item(self):