Fix `fuel2 graph execute` arguments list

According to the merged spec [1] we have the following list of args:

   fuel2 graph execute --env 1 [--nodes 1 2 3]
                                [--graph-types gtype1 gtype2]
                                [--task-names task1 task2]
                                [--force]
                                [--dry-run]

where

* ``--nodes`` executes only on passed nodes;
* ``--graph-types`` executes passed graphs within one transaction;
* ``--task-names`` executes only passed tasks skipping others;
* ``--force`` executes tasks anyway;
* ``--dry-run`` executes in dry-run mode (doesn't affect nodes)

But in fact:
[root@nailgun ~]# fuel2 graph execute
usage: fuel2 graph execute [-h] -e ENV [-t TYPES [TYPES ...]]
                           [-n NODES [NODES ...]]
                           [-T TASK_NAMES [TASK_NAMES ...]] [-d] [-f] [--noop]

So all those arguments are not really here:

[root@nailgun ~]# fuel2 graph execute --env 1 --graph-types my_graph
usage: fuel2 graph execute [-h] -e ENV [-t TYPES [TYPES ...]]
                           [-n NODES [NODES ...]]
                           [-T TASK_NAMES [TASK_NAMES ...]] [-d] [-f] [--noop]
fuel2 graph execute: error: unrecognized arguments: --graph-types my_graph

[root@nailgun ~]# shotgun2 short-report
cat /etc/fuel_build_id:
 495
cat /etc/fuel_build_number:
 495
cat /etc/fuel_release:
 9.0
cat /etc/fuel_openstack_version:
 mitaka-9.0
rpm -qa | egrep 'fuel|astute|network-checker|nailgun|packetary|shotgun':
 python-fuelclient-9.0.0-1.mos347.noarch
 fuel-setup-9.0.0-1.mos6352.noarch
 rubygem-astute-9.0.0-1.mos764.noarch
 fuel-migrate-9.0.0-1.mos8578.noarch
 shotgun-9.0.0-1.mos90.noarch
 fuel-nailgun-9.0.0-1.mos8816.noarch
 fuel-misc-9.0.0-1.mos8578.noarch
 python-packetary-9.0.0-1.mos148.noarch
 fuel-9.0.0-1.mos6352.noarch
 fuel-ui-9.0.0-1.mos2799.noarch
 nailgun-mcagents-9.0.0-1.mos764.noarch
 network-checker-9.0.0-1.mos74.x86_64
 fuel-utils-9.0.0-1.mos8578.noarch
 fuel-library9.0-9.0.0-1.mos8578.noarch
 fuel-mirror-9.0.0-1.mos148.noarch
 fuel-ostf-9.0.0-1.mos944.noarch
 fuel-notify-9.0.0-1.mos8578.noarch
 fuel-agent-9.0.0-1.mos289.noarch
 fuel-release-9.0.0-1.mos6352.noarch
 fuel-bootstrap-cli-9.0.0-1.mos289.noarch
 fuelmenu-9.0.0-1.mos275.noarch
 fuel-provisioning-scripts-9.0.0-1.mos8816.noarch
 fuel-openstack-metadata-9.0.0-1.mos8816.noarch

[1] https://review.openstack.org/#/c/343256/13/specs/10.0/graph-concept-extension.rst