Extend users and database module with additional options

[szEvEz]

• Add additional config options, like
  • login_user
  • login_host
  • login_password
  • ca_certificate

This also allows using this role for configuring users/databases for SaaS offerings, like Azure Database for MySQL. E.g.

- hosts: localhost
  vars:
    mysql_login_host: myazuredb.azure.net
    mysql_login_user: rootuser
    mysql_login_password: secret
    mysql_ca_cert: path/to/my/cert.pem
  tasks:
    - include_role:
        name: ansible-role-mysql
        tasks_from: "{{ item }}"
      loop:
        - users
        - databases