fix: elementRef.nativeElement.firstChild is null after YMapMarker and YMapControl creation

[ddubrava]

What kind of change does this PR introduce?

• [x] Bugfix
• [ ] Feature
• [ ] Refactoring
• [ ] Build or CI related changes
• [ ] Documentation content changes

Which library does this PR affect?

• [ ] angular-yandex-maps-v2
• [x] angular-yandex-maps-v3

What is the current behavior?

If we change a configuration, YMapMarker and YMapControl become broken. The API removes them from the DOM, and after a configuration change, elementRef.nativeElement.firstChild is null

What is the new behavior?

The element is saved to a separate variable, we pass it on a configuration change.

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No