Add additional config to the web part, update the playbooks

This MR adds an additional configuration that was hard-wired in the freva_web part. The web configuration is set in the inventory file and creates a freva_web.toml file that is used to configure the django settings of the web part.

I've also modified all playbooks to be able to :

a) Only create systemd service scripts if systemd is available on the system b) Set the architecure of the backend.

@k204237 @k204231