Land feature 57's controller work on its release branch

The controller plans config, templates and moved providers' provisions,
hands bus accounts to the vault and judges the new manifest words, on the
feature's SDK and node-engine validator (feature 57, config and provisioning).

internal/link/protocol_node_key_test.go

@@ -0,0 +1,11 @@
+package link
+
+import "testing"
+
+// The engine that states its sealing key to the vault at start and on change (issue 786); the same number as
+// mesh-host internal/link/messages.go's, after HandedContract (11) and VaultBoxContract (12).
+func TestNodeKeyContractIsThirteen(t *testing.T) {
+	if NodeKeyContract != 13 {
+		t.Errorf("NodeKeyContract is %d", NodeKeyContract)
+	}
+}