## 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/property_definition.py
if is_numerical:
            return dataclasses.replace(
                self, numerical_filter="AND is_numerical = true AND name NOT IN ('distinct_id', 'timestamp')"
            )
        else:
            return self
    def with_feature_flags(self, is_feature_flag: Optional[bool]) -> "QueryContext":
        if is_feature_flag is None:
            return self
        elif is_feature_flag:
            return dataclasses.replace(
                self,
                is_feature_flag_filter="AND (name LIKE %(is_feature_flag_like)s)",
                params={**self.params, "is_feature_flag_like": "$feature/%"},
            )
        elif not is_feature_flag:
            return dataclasses.replace(
                self,
                is_feature_flag_filter="AND (name NOT LIKE %(is_feature_flag_like)s)",
                params={**self.params, "is_feature_flag_like": "$feature/%"},
            )
    def with_type_filter(self, type: str, group_type_index: Optional[int]):