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/osbase/logtree/grpc.go b/osbase/logtree/grpc.go
index 3b2594d..7e17c56 100644
--- a/osbase/logtree/grpc.go
+++ b/osbase/logtree/grpc.go
@@ -1,9 +1,13 @@
 package logtree
 
-import "google.golang.org/grpc/grpclog"
+import (
+	"google.golang.org/grpc/grpclog"
+
+	"source.monogon.dev/go/logging"
+)
 
 // GRPCify turns a LeveledLogger into a go-grpc compatible logger.
-func GRPCify(logger LeveledLogger) grpclog.LoggerV2 {
+func GRPCify(logger logging.Leveled) grpclog.LoggerV2 {
 	lp, ok := logger.(*leveledPublisher)
 	if !ok {
 		// Fail fast, as this is a programming error.
@@ -71,5 +75,5 @@
 }
 
 func (g *leveledGRPCV2) V(l int) bool {
-	return g.lp.V(VerbosityLevel(l)).Enabled()
+	return g.lp.V(logging.VerbosityLevel(l)).Enabled()
 }