"Reverse-scoping": make it possible to remove certain locations from LR's scope

Currently it is possible to scope LR to a particular sub-directory of a website, but it is impossible to remove certain directories that are within the scope from it.

Consider a website like this:

/
 - admin/
 - blog/
 - assets/

It is possible to scope LR only to either /blog/ or /assets/, but it's currently impossible to scope LR to / but keep /admin/ out of scope, or to scope it only to /admin/ and /assets/ but leave /blog/ out.

This is directly caused by the scope option of the ServiceWorkerContainer.register() method being a string.

What LR could do about this is have its internal way of defining separate config branches for each sub-directory of the scoped directory, so that while the service worker is still registered and scoped to them, a directory where we do not want any special handling could be set to only go through standard fetch().