can I force a deploy to run with the api OR watch additional files?

We use kustomize with custom plugins that help us generate ConfigMaps. The ConfigMaps are based on files not directly referenced from kustomization.yaml as they are loaded by convention and/or plugin config that skaffold will not know how to parse.

### Expected behavior

When running `skaffold dev` with the API enabled, and requesting a deploy via the execute service in response to file changes, I expected a deploy would run.

### Actual behavior

No deploy runs.

My reading of the code indicates this is because none of the kustomization files skaffold knows about have changed, so it ignores the deploy request.

### Questions

I will happily code up a PR that can solve my problem. My question is what kind of solution would be accepted. I can think of two approaches:

1. The simplest solution to my problem might be a way of adding additional file patterns that can trigger a deploy. e.g.,

```yaml
deploy:
watchFiles:
- foo/**.yml
```

2. Being able to force a deploy to run through the API seems generally useful. It's more work to use, but also provides an escape hatch for other scenarios I have not considered here.