list stacks: replace the exising two RPC calls with single RPC call

[Kanagaraj Manickam]

in the implementation of engine.service.list_stacks, when the with_count is provided, there are two rpc call made between api and engine service, one for list and another for count.
This could be improved by introducing an another RPC call say list_stacks_with_metadata, where more details about stack list could be returned such as 'count' in addition to the list of stacks

{'total_count':'', <-- total number of stacks based on list stacks filter
 'count':'', <-- current list stacks count
 'stack_list': [], <- list of stacks
 'marker' : '', < --- ID of the last item in this list
 'deleted_stack_count':''
}

[Steve Baker (steve-stevebaker)]

A different name for this method would be preferred. "metadata" is already too overloaded

[Kent Wang (k.wang)]

Is this still an issue? It looks like the relevant code has been updated in latest release