New ipaclient_setup_krb5: Use ipaclient_setup_krb5 instead of ipa-krb5 role

The advantage of this is that the krb5 configuration is created in the same
way as in the normal installers. The same functionality as in the normal
installers is used in ipaclient_setup_krb5. There is no need to adapt the
ipa-krb5 role or the the ask file for changes in how the krb5 configuration
is done. Additionally ipaclient_force is now a supported parameter as
it is in the normal installer.

New config option:

ipaclient_force

The variable has been added to ipaclient/defaults/main.yml.