feat: Improve support for Ansible handlers

[haidaraM]

Related to #214 and #217

References:

• https://docs.ansible.com/ansible/latest/playbook_guide/playbooks_handlers.html
• https://docs.ansible.com/ansible/latest/playbook_guide/playbooks_reuse.html
• https://docs.ansible.com/ansible/latest/playbook_guide/playbooks_reuse_roles.html
• https://docs.ansible.com/ansible/2.9/user_guide/playbooks_reuse_includes.html

TODOs

• Make sure the graph representation and the post processor consider the handlers to highlight the nodes on hover.
• Add tests for the number of edges in the graph.
• Make the handlers in the roles are available at the play level and we can get a handler using role_name : handler_name.
• Update the mermaid renderer to draw the handlers.

[coveralls]

coverage: 95.63% (+1.8%) from 93.824%
when pulling 5569697 on improve-handlers
into b300a2c on main.