Remove extension from identifiable is synchronous

[antoinebhs]

Describe the current behavior

When calling identifiable.removeExtension(Extension.class), the server is called synchronously on each call.
For example, in this code:

        try (NetworkStoreService service = createNetworkStoreService(randomServerPort)) {
            Network network = service.getNetwork(service.getNetworkIds().keySet().iterator().next());
            Generator gen = network.getGenerator("GEN");
            gen.removeExtension(ActivePowerControl.class); // calls the server to remove the extension from the network 
            service.flush(network);
        }

This is bad for performance, if we remove extensions of a batch of identifiables for example.

Describe the expected behavior

We should buffer the removal of extensions similarly to what is done when updating/removing identifiables (see implementation of buffered network store client).
When removing the extensions on a batch of identifiables, the removal should be done in one request.

Describe the steps

No response

Environment

No response

Relevant Log Output

No response

Extra Information

No response