Add a health check executable

### Is your feature request related to a problem? Please describe.

When deploying a Node.js gRPC server in a container, there is no straight-forward way to preform a health check when using `grpc-health-check`.

### Describe the solution you'd like

It would be great to have an executable that we can run like:

```sh
npx grpc-health-check 0.0.0.0:50051
```

### Describe alternatives you've considered

In order to perform a health check within the container, there seems to be a few options currently:

- pull in an additional binary such as https://github.com/grpc-ecosystem/grpc-health-probe
- install [grpcurl](https://github.com/fullstorydev/grpcurl)
- build a custom client like https://gist.github.com/HarlemSquirrel/c635b7f78a411cf68b49614af7256117