[Feature Request] Ease handling of complex full-screen possibilities in Google Maps adapter

[acorncom]

Is your feature request related to a problem? Please describe.
As outlined in #726 (comment), our Google Maps adapter applies relatively simplistic logic to determining appropriate coordinates for drawing when in full-screen mode. This has worked fine until now, but may snag folks in the future if they have a different containing element that has been set to full-screen mode and a Google Maps element that then fills almost all of that containing element.

Describe your proposed idea for the solution to this problem
Shift the a simplistic two-choice option that we do now:

const mapElement = document.fullscreenElement ?? this._map.getDiv();

to a protected method approach that gives an extension point for folks to build out in a custom adapter if needed:

const mapElement = getBoundingMapElement(this._map); // provide access to what is otherwise a private variable

// snipped ...

// allows custom adapter overrides where needed, document further
getBoundingMapElement(map) {
  return document.fullscreenElement ?? map.getDiv();
}

Describe alternatives you've considered
We could leave it for now and see if someone asks for it. But writing this up is fresh in our minds right now and I'm looking at use case for a client that may require this in the next few months, so thought I'd write it up now

[JamesLMilner]

Firstly @acorncom thanks for think about this a bit more deeply - appreciate your help and support.

Let me think on this a little because I am trying to think about the best way to achieve this. Historically I've tended to avoid customisation of behavior via class extension (people are obviously free to do that of course!), but rather allowing people to use the default class and passing configuration arguments, but I appreciate different developers have different tastes.

I also am wondering if we need to think about full screen more broadly for other adapters and if it's a broader issue. Anyway, I will keep thinking on it and get back to you.

[acorncom]

@JamesLMilner sure, no rush on this end. And re: different tastes, fully understood there, could potentially do something like an optional callback passed to the adapters.

Haven't used the other adapters enough to know how they handle full-screen mode but in general if there is a toolbar-like DOM element that needs to survive a transition to full-screen, then I could see this being a pattern that would be nice to solve library-wide ...