Add support in quickstart to deploy standalone(on a libvirt node)

[yatin]

Support standalone deployment via quickstart.sh so it can be deployed just by running quickstart.sh like below:-

bash quickstart.sh -R master-tripleo-ci --no-clone --tags all -e @./config/environments/standalone_centos_libvirt.yml -c config/general_config/featureset052.yml 127.0.0.2

Standalone deployment (featureset052) don't need any additional node so that can be adjusted for standalone, also environment files are specific for centos7, so need to adjust so it works for centos8, Also need to write a playbook to drive the standalone deployment. Also check if any thing else missing.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/743913

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/743916

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/743919

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/744864

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/743913
Committed: https://git.openstack.org/cgit/openstack/tripleo-quickstart-extras/commit/?id=5ad637df51c553c5eae2f39cf7b0efde2f235510
Submitter: Zuul
Branch: master

commit 5ad637df51c553c5eae2f39cf7b0efde2f235510
Author: yatinkarel <email address hidden>
Date: Thu Jul 30 11:42:18 2020 +0530

    Allow to override NeutronBridgeMappings for standalone deploy

    Current default for NeutronBridgeMappings is datacentre:br-ex,
    add option to allow to configure it like datacentre:br-ctlplane
    or something else as per environment.

    Depends-On: https://review.opendev.org/#/c/744113/
    Partial-Bug: #1889219
    Change-Id: Idfd0e3f97731f5cf9005809825f47199c86ed508

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/743916
Committed: https://git.openstack.org/cgit/openstack/tripleo-quickstart-extras/commit/?id=1e299a04954479987ac368b060502dc6f64d897b
Submitter: Zuul
Branch: master

commit 1e299a04954479987ac368b060502dc6f64d897b
Author: yatinkarel <email address hidden>
Date: Thu Jul 30 12:04:22 2020 +0530

    Add playbook to deploy standalone on virthost

    Depends-On: https://review.opendev.org/#/c/744113/
    Partial-Bug: #1889219
    Change-Id: I67d37134372f9d71e4a5fc82740051b98cfdf3e1

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/744864
Committed: https://git.openstack.org/cgit/openstack/tripleo-quickstart-extras/commit/?id=d151bee4a67d1e201999cd77402474e0f30d2be9
Submitter: Zuul
Branch: master

commit d151bee4a67d1e201999cd77402474e0f30d2be9
Author: yatinkarel <email address hidden>
Date: Wed Aug 5 14:40:30 2020 +0530

    Honour standalone updates too for container-prep

    This is needed for running standalone deploy with
    container updates outside of zuul. In zuul jobs issue
    was not detected as update_containers is always
    set for zuul jobs.

    Partial-Bug: #1889219
    Change-Id: I87a0214a344a9b23dd267e412a37b2abe0eb0571

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/743919
Committed: https://git.openstack.org/cgit/openstack/tripleo-quickstart/commit/?id=814b080a60f08dc6d292138cb5a1603c6885672c
Submitter: Zuul
Branch: master

commit 814b080a60f08dc6d292138cb5a1603c6885672c
Author: yatinkarel <email address hidden>
Date: Thu Jul 30 12:22:34 2020 +0530

    Switch Standalone environment to centos8

    Following changes are done with this patch:-
    - Ussuri+ releases are CentOS8 only, switch the standalone
    environment settings to reflect the same.
    - Add some os tempest options in standalone environment
    file to get tempest run with it.
    - Enable repo setup on virthost it will be needed to get
    repos needed by DLRN run.
    - Add settings to not prepare overcloud nodes as standalone
    deploy doesn't need those.
    - Also add some vars required for standalone deployment.
    - Do not use egg_info for tripleo-quickstart-extras path to
    avoid quickstart-extras installation from pip cache and instead
    install it from specified path.

    This environment file will be used to test standalone
    deployments on ci.centos.org.

    Closes-Bug: #1889219
    Depends-On: I87a0214a344a9b23dd267e412a37b2abe0eb0571
    Change-Id: Ic17bf6e69b1620bdcca339f436e1399b29c0437e