Bug 1970252

Until now, the creation of a new validation was done with a standalone Ansible playbook:

$ cd tripleo-validations
$ export NEWROLENAME=my_new_validation
$ ansible-playbook -i localhost, role-addition.yml -e role_name=${NEWROLENAME}

The role-addition.yml playbook should be migrated to an Ansible role called validation_init, including the following features:
1- One or multiple Molecule scenario(s) to validate the functioning of the latter
2- Being able to create a new validation for development purpose (with sphinx documentation and CI molecule job configuration)
3- Being able to create a new validation without the sphinx documentation and CI parts to allow operators/customers to create their own custom validations through the CLI in a near future.

To create a new validation (point 2 above), the process will be the following:

$ git clone https://opendev.org/openstack/tripleo-validations
$ cd tripleo-validations
$ export ANSIBLE_ROLES_PATH="${PWD}/roles"
$ export NEWROLENAME=my_new_val
$ ansible-playbook -i localhost, role-addition.yml -e validation_init_role_name=my_new_val

By default, the new role will be created in tripleo-validations/roles/tripleo_my_new_val directory from a skeleton and one playbook will be added in tripleo-validations/playbooks/tripleo-my-new-val.yaml.

It will also add a new job entry into the zuul.d/molecule.yaml:

- job:
    files:
      - ^roles/tripleo_my_new_val/.*
      - ^tests/prepare-test-host.yml
      - ^ci/playbooks/pre.yml
      - ^ci/playbooks/run.yml
      - ^molecule-requirements.txt
    name: tripleo-validations-centos-8-molecule-tripleo_my_new_val
    parent: tripleo-validations-centos-8-base
    vars:
      tripleo_validations_role_name: tripleo_my_new_val

And the job name will be added into the check and gate section at the top of the molecule.yaml file.

- project:
    check:
      jobs:
        - tripleo-validations-centos-8-molecule-tripleo_my_new_val
    gate:
      jobs:
        - tripleo-validations-centos-8-molecule-tripleo_my_new_val

Finally it will add a role documentation file at doc/source/roles/role-tripleo_my_new_val.rst

To create a new validation (point 3 above), the process will be the following:

$ git clone https://opendev.org/openstack/tripleo-validations
$ cd tripleo-validations
$ export ANSIBLE_ROLES_PATH="${PWD}/roles"
$ export NEWROLENAME=my_new_val
$ ansible-playbook -i localhost, role-addition.yml -e validation_init_role_name=my_new_val -e validation_init_enabling_ci=false

Only the new role and the new playbook will be created:
- tripleo-validations/roles/tripleo_my_new_val
- tripleo-validations/playbooks/tripleo-my-new-val.yaml

No modification in zuul.d/molecule.yaml will be done and no doc/source/roles/role-tripleo_my_new_val.rst file will be created.