m/{n,t}/installer: init

This adds partial implementation of the installer [1].

It needs to be integrated with the installer bundle to become
functional.

[1] https://github.com/monogon-dev/monogon/issues/44

Change-Id: I6223e50dc02bc1ad1a8d1351b556ecba43f30a2f
Reviewed-on: https://review.monogon.dev/c/monogon/+/408
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
diff --git a/metropolis/node/build/genosrelease/BUILD.bazel b/metropolis/node/build/genosrelease/BUILD.bazel
index bd66e56..bae7f1d 100644
--- a/metropolis/node/build/genosrelease/BUILD.bazel
+++ b/metropolis/node/build/genosrelease/BUILD.bazel
@@ -11,5 +11,5 @@
 go_binary(
     name = "genosrelease",
     embed = [":go_default_library"],
-    visibility = ["//metropolis/node:__pkg__"],
+    visibility = ["//metropolis/node:__subpackages__"],
 )