Make Visibility Rules apply to Client Entities as well

[malfuu]

As discussed in #708 , the high level visibility API does not apply to client entities.
(I am defining client entities as: representation of clients added by a replicon backend in the server)
For example: Replicated client entity A has IPAddress component only visible to client entity B with Admin component

I see this as an incosistency, and would prefer if clients could be occluded as well.
VisibilityFilters applied on clients could be interesting in scenarios such as:

• purposefully hiding client entities (e.g. ghosting admins)
• not exposing sensitive client information to all clients (e.g. ip address only accessible to admins)
• and arguably most important: consistency on visibility across all replicated entities

This behavior is mostly caused by queries not expecting client entities for visibility.
Relevant functions:

• on_insert
• on_client_insert
• on_client_remove
• update_for_new_clients

The culprit for this behaviour is the usage of Without<ClientVisibility> query filter.
Personal attempts of removing this filter (+ some extra code) yielded good results in hiding clients.
I think its safe, visibility mostly works on immutable borrows of components -- but its very possible there is some footgun I have planted somewhere.

I wanted to see if you were willing to consider this.

[Shatur]

I still not sure what behavior you're suggesting. Do you want to compare client entity marker with itself?

[malfuu]

Yes, with itself and other client entities.

[Shatur]

Feel free to play with it. I'm open to this or changing the design to support this use case.

[malfuu]

Sounds good, I will be posting a small PR for this in the following week to gauge your opinion.