Merge #327 by Bencodes: Make providers_bzl public

External rules can't depend on these providers in their `bzl_library` if this is kept private to subpackages.
Closes #327

COPYBARA_INTEGRATE_REVIEW=#327 from Bencodes:patch-14 2dbebf3
PiperOrigin-RevId: 715968935
Change-Id: I7dfc8a22d49c08e4061dd209c913f656e1352f42

providers/BUILD

@@ -5,6 +5,6 @@ bzl_library(
     srcs = [
         "providers.bzl",
     ],
-    visibility = ["//:__subpackages__"],
+    visibility = ["//visibility:public"],
     deps = ["//rules:visibility_bzl"],
 )