Install and enable firewalld if it is configured for ipaserver role

ipaserver role by default tries to configure firewalld but it didn't
check if firewalld related packages were installed.

Similar to DNS and trust to AD features, install firewalld-related
packages before trying to configure firewalld.

Additionally, enable and start firewalld.service because otherwise
firewall-cmd cannot communicate with firewalld itself (it is not
starting on demand).

If and administrator considers not to use firewalld, a default for
ipaserver_setup_firewalld variable has to be set to 'no'.

Fixes: https://github.com/freeipa/ansible-freeipa/issues/116