This reverts commit f7d5e83abbe95ed06aac58f4d1a2e971fae4d186. It
breaks the Firefox and Xfce tests:
in job ‘tests.firefox.x86_64-linux’:
cannot coerce a boolean to a string
in job ‘tests.xfce.x86_64-linux’:
infinite recursion encountered
That is, you can say
security.pam.services.sshd = { options... };
instead of
security.pam.services = [ { name = "sshd"; options... } ];
making it easier to override PAM settings from other modules.