feat(Youtube Player): view loading status and load programmatically

### Feature Description

Since the ready event is not fired anymore (https://github.com/angular/components/issues/28834), I would like to know if the player has been loaded yet or not (still showing placeholder). Is there already an api for that? If so I did not find it.

Furthermore it would be great if there were a way to programmatically load the player.
(The load method is currently private to the player component.)

"Dirty" workaround:
I am accessing the placeholder via css selectors and dispatching a click event on them in order to trigger the player load.

### Use Case

Example use case: UI Button that will trigger the player to play.
=> The button label may change depending on the loaded status and the click might trigger the player to load and start.

_PS: Thanks for the wrapper component. 🙏_

Inizia con il componente Youtube Player e il suo metodo load attualmente privato, usando come contesto la issue collegata su ready-event. Definisci il completamento come un modo esposto per determinare se il Player è stato caricato e un modo pubblico per caricarlo programmaticamente, supportando il caso d'uso descritto del pulsante.

Scritto dal modello di indicizzazione a partire dal testo della issue.