This commit updates Forms code to avoid direct references to all built-in ControlValueAccessor classes, which
prevents their tree-shaking from production builds. Instead, a new static property is added to all built-in
ControlValueAccessors, which is checked when we need to identify whether a given ControlValueAccessors is a
built-in one.
PR Close#41146
Prior to this commit, a lot of internal-only class properties and methods (such as `ngOnChanges`)
of the Forms package directives were exposed on angular.io website. These fields are not expected
to be called externally (they are used/invoked by framework only), since they are part of internal
implementations of the following interfaces:
* Angular lifecycle hook interfaces
* ControlValueAccessor interface
* Validator interface
Having these internal-only fields in docs creates unnecessary noise on directive detail pages.
This commit adds the `@nodoc` annotation to these properties and methods to keep fields in the
golden files, but hide them in docs.
PR Close#38583
