support "content" in ssl map

[yoshikakbudto]

Use case:
We store all of our secrets in Hashicorp Vault. And that is true for the SSL pem
It would be nice to support a "content" parameter for the constructions like these:

---
haproxy_ssl_map:
  - content: "{{ lookup('hashi_vault', 'secret=..... }}"
    dest: /etc/ssl/private/mysite.pem
   ...

  - content: !vault |
ANSIBLE_VAULT;1.2;AES256;dev
          61323931353866666336306139373937316366366138656131323863373866376666353364373761
...

[tersmitten]

Feel free to open a pull request