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. 🙏_

Beginne mit der Youtube Player-Komponente und ihrer derzeit privaten load-Methode; verwende das verlinkte ready-event-Issue als Kontext. Definiere den Abschluss so, dass es eine offengelegte Möglichkeit gibt, festzustellen, ob der Player geladen wurde, sowie eine öffentliche Möglichkeit, ihn programmgesteuert zu laden, und unterstütze damit den beschriebenen Button-Anwendungsfall.

Vom Indexierungsmodell aus dem Issue-Text verfasst.