Consolidate provider calls to token_api.create_token
Consolidate provider calls to token_api.create_token

Ensure that token_api.create_token is only called from a single
location within the token provider common logic. This allows for
the token_provider calls to create_token to be overridden looking
towards a scenario where a provider will not actually store the
token data (ephemeral tokens).

Change-Id: Ia091ccfa4638f7307588f7c0c443b28126ee6359
bp: non-persistent-tokens

UTSA-ICS/keystone-kerberos,dstanek/keystone,jamielennox/keystone,himanshu-setia/keystone,ajayaa/keystone,MaheshIBM/keystone,blueboxgroup/keystone,vivekdhayaal/keystone,promptworks/keystone,idjaw/keystone,mahak/keystone,rodrigods/keystone,openstack/keystone,jumpstarter-io/keystone,rajalokan/keystone,nuxeh/keystone,klmitch/keystone,dstanek/keystone,jumpstarter-io/keystone,roopali8/keystone,dims/keystone,ging/keystone,takeshineshiro/keystone,nuxeh/keystone,UTSA-ICS/keystone-kerberos,dstanek/keystone,cernops/keystone,mahak/keystone,blueboxgroup/keystone,ging/keystone,promptworks/keystone,rushiagr/keystone,ilay09/keystone,idjaw/keystone,roopali8/keystone,promptworks/keystone,vivekdhayaal/keystone,klmitch/keystone,jonnary/keystone,nuxeh/keystone,maestro-hybrid-cloud/keystone,ilay09/keystone,rajalokan/keystone,cernops/keystone,jumpstarter-io/keystone,maestro-hybrid-cloud/keystone,jamielennox/keystone,rushiagr/keystone,reeshupatel/demo,ajayaa/keystone,reeshupatel/demo,jonnary/keystone,ilay09/keystone,mahak/keystone,openstack/keystone,rodrigods/keystone,rajalokan/keystone,rushiagr/keystone,takeshineshiro/keystone,dims/keystone,openstack/keystone,himanshu-setia/keystone,MaheshIBM/keystone,reeshupatel/demo,vivekdhayaal/keystone