Support Firebase predeploy, postdeploy webhooks

### The use case you're trying to solve

Call a messageSlack.sh script on postdeploy. https://firebase.google.cn/docs/cli?hl=en#hooks

### Change to the action that would solve that use case

Need to find a way to properly call the postdeploy script.

### Other considerations

Trying another manual step but would be useful to use the same extension to handle this.