Presentation: Add functions that return async iterators for paged responses

[Yato333]

Closes #6314

• Add StreamedResponseGenerator class which sends paged requests and returns a response containing an async iterator. It uses RXJS internally to fetch pages in parallel.
• Use this class for all existing API functions that send paged requests.
• Deprecate all existing functions in PresentationManager, that return responses for paged requests as arrays and add alternatives that return async iterators.

[grigasp]

Also, could we have async iterator versions of the following, too?

• getDisplayLabelDefinitionsIterator - should be simple.
• getContentIterator - could return a type { descriptor: Descriptor, total: number, items: AsyncIterableIterator<Item> }.