osbase/logtree.LeveledLogger -> go/logging.Leveled

This factors out the common leveled logger interface out of the logtree.
We want to use the same interface outside of logtree/supervisor usage
within the resolver code, which will be exposed to clients.

Change-Id: I299e76d91e8cefddf8f36f1e58432418c4694df2
Reviewed-on: https://review.monogon.dev/c/monogon/+/3411
Reviewed-by: Tim Windelschmidt <tim@monogon.tech>
Tested-by: Jenkins CI
diff --git a/go/logging/BUILD.bazel b/go/logging/BUILD.bazel
new file mode 100644
index 0000000..4a5feae
--- /dev/null
+++ b/go/logging/BUILD.bazel
@@ -0,0 +1,8 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "logging",
+    srcs = ["leveled.go"],
+    importpath = "source.monogon.dev/go/logging",
+    visibility = ["//visibility:public"],
+)