feat: add dependency shutdown and configurable service endpoints

cmd/go-omni/apigen/testdata/managed/operations.go

@@ -71,9 +71,10 @@ type countedReader struct{ io.Reader }
 
 func (c *countedReader) Close() error { svc.DownloadClosed.Add(1); return nil }
 func (l *Logic) Slow(context.Context) (*types.Receipt, error) {
+	before := svc.Closed.Load()
 	svc.Started <- struct{}{}
 	<-svc.Release
-	if svc.Closed.Load() != 0 {
+	if svc.Closed.Load() != before {
 		return nil, errors.New("dependency closed before drain")
 	}
 	return &types.Receipt{Bytes: 1}, nil