Promote standalone component helpers to public API

### Command

add

### Description

With https://github.com/angular/angular-cli/commit/e895fc7c1012796442cb7a4a3b9b3a0ec3845b0e a few standalone helpers were moved from the CDK to the schematics package. I am wondering why they were moved to a "private" section and aren't considered public API. Was this just because standalone components were still in developer preview at that time? Now that angular 15 is going to make standalone components stable could the helpers be moved outside the private section and be treated as public API?

### Describe the solution you'd like

With standalone components becoming stable these helpers should become public API as well.

### Describe alternatives you've considered

_No response_

Start with commit e895fc7c1012796442cb7a4a3b9b3a0ec3845b0e and inspect the standalone helpers moved from the CDK into the schematics package. Determine how the private section exposes them, then verify that the helpers are treated as public API and update or add the relevant coverage if the package has it.

Written by the indexing model from the issue text.