kali-finish-install: Add kali user to dialout group

This does away with the kaboxer specific setup that was just adding the kali user to the kaboxer group.  And make it a bit easier to add the user to multiple groups if we decide we want to add them to more in the future.

bin/kali-finish-install

@@ -51,17 +51,21 @@ configure_zsh() {
     done
 }
 
-configure_kaboxer() {
-    # Create the group if needed
-    addgroup --system kaboxer || true
+# This is generically named in case we want to add other groups in the future.
+configure_usergroups() {
+  # Create the kaboxer group if needed
+  addgroup --system kaboxer || true
 
-    # Add the users to the group
-    for user in $(get_user_list); do
-	echo "INFO: adding user '$user' to group 'kaboxer'"
-	adduser $user kaboxer || true
-    done
+  # kaboxer - for kaboxer
+  # dialout - for serial access
+  kali_groups="kaboxer,dialout"
+
+  for user in $(get_user_list); do
+      echo "INFO: adding user '$user' to groups '$kali_groups'"
+      usermod -a -G "$kali_groups" $user || true
+  done
 }
 
 configure_sources_list
 configure_zsh
-configure_kaboxer
+configure_usergroups