message: Make the Go //testutil:go_default_library Bazel target publicly visible.
  This allows its usage in the cross-language tests WORKSPACE.
diff: @@ -16,6 +16,7 @@ go_library(
  "@tink_base//testdata/templates",
  ],
  importpath = "github.com/google/tink/go/testutil",
  + visibility = ["//visibility:public"],
  deps = [
  "//aead:go_default_library",
  "//core/registry:go_default_library",
  