Feature/POL1-798 integrate nokia netconf polling with get-interface-stats

brian_polling_manager/interface_stats/cli.py

brian_polling_manager/interface_stats/vendors/__init__.py

brian_polling_manager/interface_stats/vendors/common.py

brian_polling_manager/interface_stats/vendors/juniper.py

brian_polling_manager/interface_stats/vendors/nokia.py

test/interface_stats/conftest.py

test/interface_stats/data/capture-test-data-nokia.py

test/interface_stats/data/capture-test-data.py

test/interface_stats/data/raw-response-juniper-sample.xml

test/interface_stats/data/raw-response-nokia-sample.xml

...ata/rt0.ams.nl.lab.office.geant.net-router-interfaces.xml

...ata/rt0.lon.uk.lab.office.geant.net-router-interfaces.xml

test/interface_stats/test_interface_stats.py

test/interface_stats/test_interface_stats_e2e.py

test/interface_stats/test_juniper.py

test/interface_stats/test_nokia.py