treewide: introduce osbase package and move things around

All except localregistry moved from metropolis/pkg to osbase,
localregistry moved to metropolis/test as its only used there anyway.

Change-Id: If1a4bf377364bef0ac23169e1b90379c71b06d72
Reviewed-on: https://review.monogon.dev/c/monogon/+/3079
Tested-by: Jenkins CI
Reviewed-by: Serge Bazanski <serge@monogon.tech>
diff --git a/metropolis/node/core/consensus/testhelpers.go b/metropolis/node/core/consensus/testhelpers.go
index 3522e06..3471e3c 100644
--- a/metropolis/node/core/consensus/testhelpers.go
+++ b/metropolis/node/core/consensus/testhelpers.go
@@ -6,7 +6,7 @@
 
 	clientv3 "go.etcd.io/etcd/client/v3"
 
-	"source.monogon.dev/metropolis/pkg/event/memory"
+	"source.monogon.dev/osbase/event/memory"
 )
 
 type testServiceHandle struct {