dockerTools.buildLayeredImage: image names with registry/ prefix

When using `buildLayeredImage`, it is not possible to specify an image
name of the form `<registry>/my/image`, although it is a valid name.

This is due to derivations under `buildLayeredImage` using that image
name as their derivation name, but slashes are not permitted in that
context.

A while ago, #13099 fixed that exact same problem in `buildImage` by
using `baseNameOf name` in derivation names instead of `name`. This
change does the same thing for `buildLayeredImage`.

nixos/tests/docker-tools.nix

@@ -254,5 +254,21 @@ import ./make-test-python.nix ({ pkgs, ... }: {
             "docker run --rm ${examples.layeredStoreSymlink.imageName} bash -c 'test -L ${examples.layeredStoreSymlink.passthru.symlink}'",
             "docker rmi ${examples.layeredStoreSymlink.imageName}",
         )
+
+    with subtest("buildImage supports registry/ prefix in image name"):
+        docker.succeed(
+            "docker load --input='${examples.prefixedImage}'"
+        )
+        docker.succeed(
+            "docker images --format '{{.Repository}}' | grep -F '${examples.prefixedImage.imageName}'"
+        )
+
+    with subtest("buildLayeredImage supports registry/ prefix in image name"):
+        docker.succeed(
+            "docker load --input='${examples.prefixedLayeredImage}'"
+        )
+        docker.succeed(
+            "docker images --format '{{.Repository}}' | grep -F '${examples.prefixedLayeredImage.imageName}'"
+        )
   '';
 })