Unable to use client attr because it is used by our client

[ruscoder]

Let's remove self.client to self._client

[ruscoder]

I'm thinking about _client extenstion in FHIR Resources, so, maybe to choose another name

[ruscoder]

Renamed to __client__ in 2.0.0

[ruscoder]

sessions = (
            await fhir_client.resources("Session")
            .search(Raw(**{"user:User.id": user.id}))
            .fetch_all()
        )

raises

TypeError: BaseResource.__init__() got multiple values for argument 'client'

because the first argument of BaseResource is still named client.
It needs to be renamed as well.