user roles have to be unique

[4nt01ne]

We have more than 100 roles and about 60 users.
Same roles are allowed on multiple security-setting match.
If one role is configured more than once in the activemq_roles it is duplicated each time in artemis-roles.properties.

This PR is a suggestion to remove duplicate roles.

FYI: this PR is from my private account behind AWD09. We have migrated to GH Enterprise and I am not allowed to open issues or fork repos on my pro account anymore.
We are using the amq_broker playbook.

STEPS TO REPRODUCE

---

- name: reproduce roles generation
  hosts: localhost
  vars:
    amq_broker_users:
      - user: one
        password: abc
        roles: [ role_a ]
      - user: two
        password: abc
        roles: [ role_a, role_b ]
    amq_broker_roles:
      - match: a.queue.*
        name: role_a
        permissions: [ createAddress, createDurableQueue, createNonDurableQueue, deleteAddress, deleteDurableQueue, deleteNonDurableQueue, manage, send ]
      - match: an.other.queue.*
        name: role_b
        permissions: [ createAddress, createDurableQueue, createNonDurableQueue, deleteAddress, deleteDurableQueue, deleteNonDurableQueue, manage, send ]
      - match: a.last.queue.*
        name: role_a
        permissions: [ manage, send ]
  tasks:
    - name: Configure roles
      ansible.builtin.template:
        src: artemis-roles.properties.j2
        dest: artemis-roles.properties

The content of artemis-roles.properties is

role_a=one,two
role_b=two
role_a=one,two

'role_a' is present 2 times