## 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The UX problem this is causing is that the "Last refreshed" label now introduced in the dashboards gets outdated because `items` doesn't get updated. Having this object with outdated information also leads to other confusing UX issues.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/tasks/update_cache.py
return getattr(importlib.import_module(module), name)
def _calculate_by_filter(filter: FilterType, key: str, team_id: int, cache_type: CacheType) -> List[Dict[str, Any]]:
    dashboard_items = DashboardItem.objects.filter(team_id=team_id, filters_hash=key)
    dashboard_items.update(refreshing=True)
    if is_clickhouse_enabled():
        insight_class_path = CH_TYPE_TO_IMPORT[cache_type]
    else:
        insight_class_path = TYPE_TO_IMPORT[cache_type]
    insight_class = import_from(insight_class_path[0], insight_class_path[1])
    result = insight_class().run(filter, Team(pk=team_id))
    dashboard_items.update(last_refresh=timezone.now(), refreshing=False)
    return result
def _calculate_funnel(filter: Filter, key: str, team_id: int) -> List[Dict[str, Any]]:
    dashboard_items = DashboardItem.objects.filter(team_id=team_id, filters_hash=key)
    dashboard_items.update(refreshing=True)
    if is_clickhouse_enabled():
        insight_class = import_from("ee.clickhouse.queries.clickhouse_funnel", "ClickhouseFunnel")
    else:
        insight_class = import_from("posthog.queries.funnel", "Funnel")
    result = insight_class(filter=filter, team=Team(pk=team_id)).run()
    dashboard_items.update(last_refresh=timezone.now(), refreshing=False)
    return result