## 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The UX problem this is causing is that the "Last refreshed" label now introduced in the dashboards gets outdated because `items` doesn't get updated. Having this object with outdated information also leads to other confusing UX issues.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
item = DashboardItem.objects.create(dashboard=dashboard, filters=filter_dict, team=self.team,)
        DashboardItem.objects.create(
            dashboard=dashboard, filters=filter.to_dict(), team=self.team,
        )
        self.client.get(
            "/api/insight/trend/?events=%s&properties=%s&date_from=-7d"
            % (json.dumps(filter_dict["events"]), json.dumps(filter_dict["properties"]))
        )
        patch_response = self.client.patch(
            "/api/dashboard/%s/" % dashboard.pk, {"filters": {"date_from": "-24h"}}, format="json",
        ).json()
        self.assertEqual(patch_response["items"][0]["result"], None)
        
        response = self.client.get(
            "/api/insight/trend/?events=%s&properties=%s&date_from=-24h"
            % (json.dumps(filter_dict["events"]), json.dumps(filter_dict["properties"]))
        )
        self.assertEqual(response.status_code, 200)
        item = DashboardItem.objects.get(pk=item.pk)
        
        response = self.client.get("/api/dashboard/%s/" % dashboard.pk).json()
        self.assertEqual(len(response["items"][0]["result"][0]["days"]), 2)  
    def test_invalid_properties(self):
        properties = "invalid_json"
        response = self.client.get(f"/api/insight/trend/?properties={properties}")
        self.assertEqual(response.status_code, 400)
        self.assertDictEqual(
            response.json(), self.validation_error_response("Properties are unparsable!", "invalid_input")
        )