## Is your feature request related to a problem?

As a team accumulates data, they will have events/properties that are no longer in use that clutter their app.

Example from our team:
![image](https://user-images.githubusercontent.com/148820/143202334-42d73ab6-13be-4661-ba7a-83c86788b9e8.png)


## Describe the solution you'd like

Under event/properties stats allow 'hiding' events/properties from view.

## Describe alternatives you've considered

Alternatively, go the route of "verified" events/properties (as He@p) does - show those first. See also https://help.heap.io/category/heap-administration/data-governance/

## Additional context

Note: Existing reports, etc should still work well even with 'removed' events/properties.

Related: https://github.com/PostHog/posthog/issues/7126

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

posthog/api/test/test_property_definition.py
assert sorted(
            [(r["name"], r["is_seen_on_filtered_events"]) for r in response.json()["results"]], key=lambda tup: tup[0]
        ) == [
            ("$browser", True),
            ("$current_url", False),
            ("app_rating", False),
            ("first_visit", True),
            ("is_first_movie", False),
            ("plan", False),
            ("purchase", False),
            ("purchase_value", False),
        ]
        
        response = self.client.get(
            f"/api/projects/{self.team.pk}/property_definitions/?event_names=%5B%22%24pageview%22%5D&filter_by_event_names=true"
        )
        self.assertEqual(response.status_code, status.HTTP_200_OK)
        assert sorted(
            [(r["name"], r["is_seen_on_filtered_events"]) for r in response.json()["results"]], key=lambda tup: tup[0]
        ) == [
            ("$browser", True),
            ("first_visit", True),
        ]
        
        response = self.client.get(
            "/api/projects/@current/property_definitions/?search=firs&event_names=%5B%22%24pageview%22%5D&filter_by_event_names=true"
        )
        self.assertEqual(response.status_code, status.HTTP_200_OK)
        self.assertEqual(