Support of additional SAN for etcd

[danopt]

Fixes #48

To support etcd the IP addresses and the loopback address has to be defined in the SAN.

To achieve this a temporary variable ca_san will be defined with set_fact. I also implemented the support of custom additional SANs with the variable ca_san_custom.

This is the value of the variable ca_san, after it is defined with set_fact and the whitespaces are removed with regex_replace():
`DNS:rockylinux-8-03,DNS:rockylinux-8-03,DNS:vm-3,IP:127.0.0.1,IP:10.0.53.15,IP:10.0.53.15,IP:10.0.53.15'

The string of ca_san_custom variable has to begin with a ',' and could look like this to add the IP address of a second NIC (will be combined with ca_san):

    ca_san_custom:  >-
      ,
      {%- for host in vars['play_hosts'] -%}
        IP:{{ hostvars[inventory_hostname].ansible_eth1.ipv4.address }}
        {%- if not loop.last -%}
          ,
        {%- endif -%}
      {%- endfor -%}

[widhalmt]

I got a few annotations. To be honest, I couldn't test the whle code so there might still be typos in my version. But I hope I could show what I intended.

[widhalmt]

Could you have a look at my comment? Maybe I misunderstood your change but if I see it correctly it might break any option of using the role for anything else than etcd when the etcd option is set. That's ok but please make it clear in the Readme.

[danopt]

Changes:

• Added molecule verification tasks

[danopt]

Fixes #56

[widhalmt]

This looks very, very good! Thanks for the great contribution!

[danopt]

Thx. Not a problem at all. ;-)