Add "disk-dlc" group

This is a group which will be used to grant read/write permission on
certain devices (specifically logical volumes) with udev permission
rules that pertain to DLC images [A|B].

BUG=b:236007986
TEST=chromeos-base

Change-Id: I5f6d051276c376045095774ddf8201ef5a389dd0
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/eclass-overlay/+/3885157
Commit-Queue: Jae Hoon Kim <kimjae@chromium.org>
Reviewed-by: Allen Webb <allenwebb@google.com>
Tested-by: Jae Hoon Kim <kimjae@chromium.org>
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
diff --git a/profiles/base/accounts/group/disk-dlc b/profiles/base/accounts/group/disk-dlc
new file mode 100644
index 0000000..d92b8ea
--- /dev/null
+++ b/profiles/base/accounts/group/disk-dlc
@@ -0,0 +1,3 @@
+group:disk-dlc
+gid:20777
+users:root,dlcservice,imageloaderd