m/pkg/logtree: implement concise stringification

This adds a new method on LogEntry: ConciseString(). It's designed to
be used in cases where we want to display the log line on some
limited-width (and likely non-interactive) log console, like TTY
consoles in Metropolis.

This is a bit too Metropolis-specific to my liking (we hardcode some
logic related to the layout of root.role.*), but it'll do for now.

Change-Id: I1079b8b19a3c304fcc5077ce6b4c69887a34d7ae
Reviewed-on: https://review.monogon.dev/c/monogon/+/1359
Reviewed-by: Leopold Schabel <leo@monogon.tech>
Tested-by: Jenkins CI
diff --git a/metropolis/pkg/logtree/BUILD.bazel b/metropolis/pkg/logtree/BUILD.bazel
index aabc40d..5c4237c 100644
--- a/metropolis/pkg/logtree/BUILD.bazel
+++ b/metropolis/pkg/logtree/BUILD.bazel
@@ -21,6 +21,7 @@
     deps = [
         "//metropolis/pkg/logbuffer",
         "//metropolis/proto/api",
+        "@com_github_mitchellh_go_wordwrap//:go-wordwrap",
         "@org_golang_google_protobuf//types/known/timestamppb",
     ],
 )