chore: restructure bazel macros

hack/bazel/docker/BUILD.bazel

@@ -0,0 +1 @@
+package(default_visibility = ["//visibility:public"])

hack/bazel/docker/publish.bzl

@@ -0,0 +1,17 @@
+load("@io_bazel_rules_docker//container:container.bzl", "container_push")
+
+def publish(
+    service, 
+    name = "+publish", 
+    image = ":image",
+    prefix = "roleypoly/roleypoly/",
+    registry = "docker.pkg.github.com",
+):
+    container_push(
+        name = name,
+        format = "Docker",
+        image = image,
+        registry = registry,
+        repository = prefix + service,
+        tag = "{STABLE_URL_SAFE_TAG}",
+    )