metropolis/pkg/logtree: move logtree protobuf definition to logtree pkg

Before this change we had the LogEntry message inside the metropolis
common proto file. This splits it out into the logtree package to make
it standalone in a future change.

Change-Id: Idb26a829d6174efa946a6c4ce0f1b984cb2f18a2
Reviewed-on: https://review.monogon.dev/c/monogon/+/3080
Tested-by: Jenkins CI
Reviewed-by: Serge Bazanski <serge@monogon.tech>
diff --git a/metropolis/cli/metroctl/BUILD.bazel b/metropolis/cli/metroctl/BUILD.bazel
index 9eb0aa4..37f4b56 100644
--- a/metropolis/cli/metroctl/BUILD.bazel
+++ b/metropolis/cli/metroctl/BUILD.bazel
@@ -49,6 +49,7 @@
         "//metropolis/pkg/blkio",
         "//metropolis/pkg/fat32",
         "//metropolis/pkg/logtree",
+        "//metropolis/pkg/logtree/proto",
         "//metropolis/proto/api",
         "//metropolis/proto/common",
         "//version",