Password with special characters are not encoded correctly in URLs

[Benjamin FÜHRMANN]

In various configuration file in OpenStack and side services, URL can be declared to access to database or RabbitMQ.

If you use special characters like `#` or `/` in the password, then the URL is not declared as expected and related service can't load correctly the URL, causing connection/authentication issues.

To fix that issue, we can use the `urlencode` filter in Ansible to encode the password.

Example:

```
[database]
connection = mysql+pymysql://{{ ironic_database_user }}:{{ ironic_database_password | urlencode }}@{{ ironic_database_address }}/{{ ironic_database_name }}
```

[Benjamin FÜHRMANN (fuhrmannb)]

Note that we have to also encode slashes manually, Jinja does not do it in `urlencode` method. See [related Jinja2 issue](https://github.com/pallets/jinja/issues/515).

Final Example:

```
[database]
connection = mysql+pymysql://{{ ironic_database_user }}:{{ ironic_database_password | urlencode | replace('/', '%2f') }}@{{ ironic_database_address }}/{{ ironic_database_name }}
```

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/kolla-ansible/+/841865

[Dr. Jens Harbott (j-harbott)]

IMHO it should be enough to simply document the restriction