ipa[server,replica,client]: RHEL-8 specific vars files

These vars files are providing the module names used with the Ansible
package module to install the needed RPM packages.

roles/ipaclient/vars/RedHat-8.yml

+# defaults file for ipaclient
+# vars/RedHat-8.yml
+ipaclient_packages: [ "@idm:DL1/client" ]

roles/ipareplica/vars/RedHat-8.yml

+# defaults file for ipareplica
+# vars/RedHat-8.yml
+ipareplica_packages: [ "@idm:DL1/server" ]
+ipareplica_packages_dns: [ "@idm:DL1/dns" ]
+ipareplica_packages_adtrust: [ "@idm:DL1/adtrust" ]

roles/ipaserver/vars/RedHat-8.yml

+# defaults file for ipaserver
+# vars/RedHat-8.yml
+ipaserver_packages: [ "@idm:DL1/server" ]
+ipaserver_packages_dns: [ "@idm:DL1/dns" ]
+ipaserver_packages_adtrust: [ "@idm:DL1/adtrust" ]