How to specify the renderer to use when deploying Flutter projects to firebase

### [REQUIRED] Environment info

**firebase-tools:12.3.0

**Platform:macOS

### [REQUIRED] Test case

### [REQUIRED] Steps to reproduce
1. Run `flutter create ` to create a Flutter app, then cd into the directory
2. Run `firebase experiments:enable webframeworks`
3. Run `firebase init hosting --project `, which will show a prompt

When running `firebase deploy`, How do I specify the renderer to use i.e a `firebase deploy` command that maps to `firebase deploy --renderer canvaskit`

### [REQUIRED] Expected behavior
Ability to specify the renderer to use and extra `flutter build web` parameters.

### [REQUIRED] Actual behavior
`firebase deploy --help` doesn't provide this info.

It would be nice if firebase deploy --help would show this information if it's possible.