eclass-overlay: Add federated-service user and group

Set up user and group for running the Federated Computation service in
minijail.

BUG=chromium:1020051
TEST=profiles/base/accounts/display-accts.py

Change-Id: If4d103e678fa8058f925dc092870518115326a48
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/eclass-overlay/+/2355371
Tested-by: Xinglong Luan <alanlxl@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Andrew Moylan <amoylan@chromium.org>
diff --git a/profiles/base/accounts/group/federated-service b/profiles/base/accounts/group/federated-service
new file mode 100644
index 0000000..cdbbca9
--- /dev/null
+++ b/profiles/base/accounts/group/federated-service
@@ -0,0 +1,3 @@
+group:federated-service
+gid:20151
+users:federated-service
diff --git a/profiles/base/accounts/user/federated-service b/profiles/base/accounts/user/federated-service
new file mode 100644
index 0000000..25aa9e9
--- /dev/null
+++ b/profiles/base/accounts/user/federated-service
@@ -0,0 +1,6 @@
+user:federated-service
+uid:20151
+gid:20151
+gecos:CrOS Federated Computation service
+home:/dev/null
+shell:/bin/false