Revise user activation model

[marcoscaceres]

This PR brought in new user activation requirement that is a bit "unusual" (unorthodox?):
#1029

We should look at that again and figure out how to do that in a way that integrates better with the platform overall.

(for example, Screen Wake Lock allows re-requesting a lock without permission if the sticky activation was acquired via the API itself - so that achieves the no prompting requirement, while using existing infrastructure).

cc @stephenmcgruer

[ianbjacobs]

Hi @marcoscaceres, is this a duplicate of #1022?

[rsolomakhin]

Hi @marcoscaceres, can you help us understand in more details how does https://developer.mozilla.org/en-US/docs/Web/API/Screen_Wake_Lock_API apply to the user activation model? Thank you!