Don't ask for notifications in Chrome PWAs

Chrome, and most other Chromium-based browsers automatically handle the permission request, and do not show any prompts to the user. Instead, if a site is considered important, the persistent storage permission is automatically granted, otherwise it is silently denied.

The heuristics to determine if a site is important include:

How high is the level of site engagement?
_Has the site been installed or bookmarked?_
Has the site been granted permission to show notifications?
If the request was denied, it can be requested again later and will be evaluated using the same heuristics.```