m/n/core/mgmt: implement node-local management service

Change-Id: I1e8a8ff46d1172e00f2d991ae3cc3af1929b6e4e
Reviewed-on: https://review.monogon.dev/c/monogon/+/1428
Tested-by: Jenkins CI
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
diff --git a/metropolis/proto/api/management.proto b/metropolis/proto/api/management.proto
index a5fd47d..012bb07 100644
--- a/metropolis/proto/api/management.proto
+++ b/metropolis/proto/api/management.proto
@@ -180,3 +180,8 @@
 
 message UpdateNodeRolesResponse {
 }
+
+// NodeManagement runs on every node of the cluster and providers management
+// and troubleshooting RPCs to operators. All requests must be authenticated.
+service NodeManagement {
+}
\ No newline at end of file