Allow filtering by host on list_services

[ghost]

When using the list_services, I figured that I needed to filter the list of services received depending on the host
(i.e. only receiving the services running on xxx.xxx.0.22 for example)

I had two options :
Filtering the list post request by using discover()
-> Pro: no additional processing on the registry
-> Con: add a lot of calls to discover() so more demanding for the network, as well as slower execution time.

Filtering the list during the request by sending an additional parameter:
-> Pro: no extra charge on the network, and faster execution time.
-> Con: some processing is needed on the registry

I went with the second option since speed of execution is more critical.

[comrumino]

I'd be more inclined to approve this if there are unit tests. Otherwise, I will likely put it off until I write unit tests for it. But, I do appreciate the contribution 🥇

[ghost]

I will add some unit tests.