feat(gengapic): raise Operation errors from diregapic

[quartzmo]

closes: #1320

Partial diff after running bazelisk build //google/cloud/compute/v1:compute_go_gapic locally:

diff --git a/compute/apiv1/operations.go b/compute/apiv1/operations.go
index 0f77e7e2a0..d916441204 100755
--- a/compute/apiv1/operations.go
+++ b/compute/apiv1/operations.go
@@ -18,10 +18,13 @@ package compute

 import (
        "context"
+       "fmt"
        "time"

        computepb "cloud.google.com/go/compute/apiv1/computepb"
        gax "github.com/googleapis/gax-go/v2"
+       "github.com/googleapis/gax-go/v2/apierror"
+       "google.golang.org/api/googleapi"
 )

 // Operation represents a long-running operation for this API.
@@ -87,6 +90,14 @@ func (h *regionOperationsHandle) Poll(ctx context.Context, opts ...gax.CallOptio
                return err
        }
        h.proto = resp
+       if resp.HttpErrorStatusCode != nil && (resp.GetHttpErrorStatusCode() < 200 || resp.GetHttpErrorStatusCode() > 299) {
+               aErr := &googleapi.Error{
+                       Code:    int(resp.GetHttpErrorStatusCode()),
+                       Message: fmt.Sprintf("%s: %v", resp.GetHttpErrorMessage(), resp.GetError()),
+               }
+               err, _ := apierror.FromError(aErr)
+               return err
+       }
        return nil
 }
...