adds missing endpoints in tasks-svc

[PaulKalho]

Which issues does this pull request close?

closes #703

I had to alter the proto definition of getPatientListResponse a bit, now we don't need two Patient types

[MaxSchaefer]

Response of GetPatientDetails. Take a look at the assigned_user_id. Same for GetPatientList and GetTasksByPatient.

{
    "tasks": [
        {
            "subtasks": [],
            "id": "14724cf7-175b-4804-ba90-e922d4603745",
            "name": "asd",
            "description": "test",
            "status": "TASK_STATUS_IN_PROGRESS",
            "patient_id": "",
            "public": false,
            "assigned_user_id": "00000000-0000-0000-0000-000000000000"
        }
    ],
    "id": "643afb22-c8f6-4dd8-909b-303fa58cc3ad",
    "human_readable_identifier": "asd",
    "notes": "asd",
    "is_discharged": false
}

Cannot test GetPatientByBed, GetPatientByBed, GetPatientAssignmentByWard because I cannot create beds and wards.