add `_to_curl` to rpc client

[disjukr]

# it sends http request
client.get_daily_customers(UUID('E90F29EC-E77A-4327-B290-7A0EFA6B66EF'))

# no side effect. returns curl cli string
client.get_daily_customers_to_curl(UUID('E90F29EC-E77A-4327-B290-7A0EFA6B66EF'))