Add service/endpoint discover to verify_tempest_config
Add service/endpoint discover to verify_tempest_config

This commit adds a check to verify_tempest_config for which services
are available. This is used to do 2 things:

1. Verify that the entries in the service_availble group are set correctly
2. Use for filtering which checks inside the script are valid to perform

Partially implements bp config-verification

Change-Id: Ib0e55f21b83d0746994e7e7e1f9666524e1bb3b7

Tesora/tesora-tempest,pczerkas/tempest,vedujoshi/tempest,jaspreetw/tempest,yamt/tempest,akash1808/tempest,jamielennox/tempest,pczerkas/tempest,Vaidyanath/tempest,manasi24/jiocloud-tempest-qatempest,izadorozhna/tempest,Lilywei123/tempest,alinbalutoiu/tempest,roopali8/tempest,varunarya10/tempest,openstack/tempest,masayukig/tempest,flyingfish007/tempest,afaheem88/tempest,cloudbase/lis-tempest,danielmellado/tempest,neerja28/Tempest,manasi24/tempest,tudorvio/tempest,manasi24/jiocloud-tempest-qatempest,cisco-openstack/tempest,rakeshmi/tempest,tonyli71/tempest,hayderimran7/tempest,rzarzynski/tempest,zsoltdudas/lis-tempest,akash1808/tempest,dkalashnik/tempest,sebrandon1/tempest,nunogt/tempest,danielmellado/tempest,cisco-openstack/tempest,cloudbase/lis-tempest,Mirantis/tempest,FujitsuEnablingSoftwareTechnologyGmbH/tempest,afaheem88/tempest_neutron,CiscoSystems/tempest,queria/my-tempest,alinbalutoiu/tempest,Lilywei123/tempest,izadorozhna/tempest,FujitsuEnablingSoftwareTechnologyGmbH/tempest,hpcloud-mon/tempest,JioCloud/tempest,sebrandon1/tempest,roopali8/tempest,bigswitch/tempest,Juniper/tempest,varunarya10/tempest,redhat-cip/tempest,vedujoshi/os_tempest,ebagdasa/tempest,redhat-cip/tempest,vedujoshi/tempest,LIS/lis-tempest,afaheem88/tempest,zsoltdudas/lis-tempest,NexusIS/tempest,JioCloud/tempest,masayukig/tempest,jamielennox/tempest,pandeyop/tempest,eggmaster/tempest,Vaidyanath/tempest,LIS/lis-tempest,ebagdasa/tempest,Juniper/tempest,bigswitch/tempest,rzarzynski/tempest,pandeyop/tempest,yamt/tempest,Juraci/tempest,Mirantis/tempest,Tesora/tesora-tempest,flyingfish007/tempest,hpcloud-mon/tempest,eggmaster/tempest,afaheem88/tempest_neutron,vmahuli/tempest,dkalashnik/tempest,vmahuli/tempest,manasi24/tempest,Juraci/tempest,neerja28/Tempest,hayderimran7/tempest,rakeshmi/tempest,NexusIS/tempest,vedujoshi/os_tempest,jaspreetw/tempest,queria/my-tempest,tonyli71/tempest,nunogt/tempest,xbezdick/tempest,CiscoSystems/tempest,tudorvio/tempest,openstack/tempest,xbezdick/tempest