Update installer commands for REX plugin

[adamruzicka]

Cherry-pick into:

• Foreman 3.3
• Foreman 3.2
• Foreman 3.1
• For Foreman 3.0 or older, file a separate PR request

Follows up on #1301

#  rpm -q foreman
foreman-3.3.0-0.5.rc1.el7.noarch

# foreman-installer --full-help | grep remote-execution-ssh

# foreman-installer --full-help | grep remote-execution-script
    --[no-]enable-foreman-proxy-plugin-remote-execution-script Enable 'foreman_proxy_plugin_remote_execution_script' puppet module (default: true)
    --foreman-proxy-plugin-remote-execution-script-cockpit-integration  Enables/disables Cockpit integration (current: true)
    --reset-foreman-proxy-plugin-remote-execution-script-cockpit-integration Reset cockpit_integration to the default value (true)
    --foreman-proxy-plugin-remote-execution-script-mode  Operation Mode of the plugin. (current: "pull-mqtt")
    --reset-foreman-proxy-plugin-remote-execution-script-mode Reset mode to the default value ("ssh")
    --foreman-proxy-plugin-remote-execution-script-enabled  Enables/disables the plugin (current: true)
    --reset-foreman-proxy-plugin-remote-execution-script-enabled Reset enabled to the default value (true)
    --foreman-proxy-plugin-remote-execution-script-listen-on  Proxy feature listens on https, http, or both (current: "https")
    --reset-foreman-proxy-plugin-remote-execution-script-listen-on Reset listen_on to the default value ("https")
    --foreman-proxy-plugin-remote-execution-script-generate-keys  Automatically generate SSH keys (current: true)
    --reset-foreman-proxy-plugin-remote-execution-script-generate-keys Reset generate_keys to the default value (true)
    --foreman-proxy-plugin-remote-execution-script-install-key  Automatically install generated SSH key to root authorized keys
    --reset-foreman-proxy-plugin-remote-execution-script-install-key Reset install_key to the default value (false)
    --foreman-proxy-plugin-remote-execution-script-local-working-dir  Local working directory on the smart proxy (current: "/var/tmp")
    --reset-foreman-proxy-plugin-remote-execution-script-local-working-dir Reset local_working_dir to the default value ("/var/tmp")
    --foreman-proxy-plugin-remote-execution-script-remote-working-dir  Remote working directory on clients (current: "/var/tmp")
    --reset-foreman-proxy-plugin-remote-execution-script-remote-working-dir Reset remote_working_dir to the default value ("/var/tmp")
    --foreman-proxy-plugin-remote-execution-script-ssh-identity-dir  Directory where SSH keys are stored (current: "/var/lib/foreman-proxy/ssh")
    --reset-foreman-proxy-plugin-remote-execution-script-ssh-identity-dir Reset ssh_identity_dir to the default value ("/var/lib/foreman-proxy/ssh")
    --foreman-proxy-plugin-remote-execution-script-ssh-identity-file  Provide an alternative name for the SSH keys (current: "id_rsa_foreman_proxy")
    --reset-foreman-proxy-plugin-remote-execution-script-ssh-identity-file Reset ssh_identity_file to the default value ("id_rsa_foreman_proxy")
    --foreman-proxy-plugin-remote-execution-script-ssh-kerberos-auth  Enable kerberos authentication for SSH (current: false)
    --reset-foreman-proxy-plugin-remote-execution-script-ssh-kerberos-auth Reset ssh_kerberos_auth to the default value (false)
    --foreman-proxy-plugin-remote-execution-script-ssh-keygen  Location of the ssh-keygen binary (current: "/usr/bin/ssh-keygen")
    --reset-foreman-proxy-plugin-remote-execution-script-ssh-keygen Reset ssh_keygen to the default value ("/usr/bin/ssh-keygen")
    --foreman-proxy-plugin-remote-execution-script-ssh-log-level  Configure ssh client LogLevel (current: UNDEF)
    --reset-foreman-proxy-plugin-remote-execution-script-ssh-log-level Reset ssh_log_level to the default value (UNDEF)

[melcorr]

Thank you @adamruzicka

[melcorr]

Cherry-pick:
fd080c7..95ef241 3.3 -> 3.3