Configure enabled and disabled extensions in tempest
Configure enabled and disabled extensions in tempest

This patch adds support for configuring the api_extensions
option of the various feature-$service-(enabled|disabled)
sections in tempest's configuration file.

Please note that enabled extensions for the object storage
service are specified in tempest using the discoverable_apis
configuration options.

Partially-implements: Blueprint branchless-tempest-extensions

Change-Id: Ib64c0a474b153f42f3a4a427d86275c85f107997

avvocatodemarchis/devstack,andrewrothstein/devstack,neerja28/Devstack_GlusterFS,andrewrothstein/devstack,kplus/devstack-moonshot,flavio-fernandes/devstack,ozamiatin/devstack,varunarya10/devstack,tianweizhang/devstack,eshnil2000/devstack,bswartz/devstack,nawawi/openstack,mc2014/devstack,openstack-dev/devstack,kplus/devstack-moonshot,Mahito/devstack,upadhyay-prashant/devstack,wenhuizhang/devstack,bq-xiao/devstack,vishnugonela/devstack,nuxeh/devstack,openstack-dev/devstack,costingalan/devstack,sequenceiq/devstack,olivierlemasle/devstack,promptworks/devstack,bljgaurav/openstack-test,affo/devstack,liuquansheng47/devstack,herrsechs/devstack,noironetworks/devstack,richliu/devstack,TwinkleChawla/devstack,samgoon/devstack,bljgaurav/openstack-test,bigswitch/devstack,pombredanne/devstack,CloudServer/devstack,mmasaki/devstack,wenhuizhang/devstack,LoHChina/devstack,nawawi/openstack,nuxeh/devstack,costingalan/devstack,varunarya10/devstack,herrsechs/devstack,ozamiatin/devstack,noironetworks/devstack,virtualopensystems/devstack,mssumanth/devstack,atulpatil301/devstack,affo/devstack,avvocatodemarchis/devstack,NaokiMiyata/devstack,sequenceiq/devstack,atulpatil301/devstack,pacinete/devstack,promptworks/devstack,HPCHub/devstack,liuquansheng47/devstack,vishnugonela/devstack,bq-xiao/devstack,flavio-fernandes/devstack,pombredanne/devstack,LoHChina/devstack,parul24/devstack,HPCHub/devstack,Mahito/devstack,thomasem/devstack,BSJAIN92/OpenStack,richliu/devstack,upadhyay-prashant/devstack,TwinkleChawla/devstack,group-policy/devstack,samgoon/devstack,rushiagr/devstack,sc68cal/devstack,dtroyer/devstack,dirkmueller/devstack,sc68cal/devstack,eharney/devstack,thomasem/devstack,j4/devstack,group-policy/devstack,pczerkas/devstack,NaokiMiyata/devstack,mssumanth/devstack,mc2014/devstack,pacinete/devstack,bigswitch/devstack,eharney/devstack,olivierlemasle/devstack,vsham20/devstack,prithivm/branch01,rushiagr/devstack,pczerkas/devstack,dirkmueller/devstack,dtroyer/devstack,j4/devstack,parul24/devstack,bswartz/devstack,CloudServer/devstack,neerja28/Devstack_GlusterFS,vsham20/devstack,tianweizhang/devstack,mmasaki/devstack,BSJAIN92/OpenStack,prithivm/branch01