To accomodate the raccoon knights workstation, some of the configuration
pulled by m/common/main.nix has to be removed. To solve it, the xeon
specific parts are placed into m/common/xeon.nix and only the common
configuration is at m/common/base.nix.
The users.jungleUsers configuration option behaves like the users.users
option, but defines the list attribute `hosts` for each user, which
filters users so that only the user can only access those hosts.
The module is only enabled on Hut and Eudy because we noticed activity
on the debuginfod service even if no debug session was active.
Reviewed-by: Rodrigo Arias Mallo <rodrigo.arias@bsc.es>