Feat: more generic rule to skip history API

[christophe-g]

First of all, thanks a lot for this ! it is really well thought through, esp. the way to nest <router-slot>, and allow relative router (smth all other web-component friendly routing lib I had a look at fail to do properly).

The old Polymer <app-location> had a parameter to skip url from being handled by the router based on a regex.

You could for instance do <app-location route="{{route}}" url-space-regex="^(?!/api/).+"></app-location> to skip all url starting with /api.

In app-router, you'd need to add data-router-slot=disabled to all such links. It would be more convenient in some cases to rely on a more generic rule.

I can have a go at trying to add this feature if this is something you might consider adding.

The main difficulty is to find a proper way to inject this additional logic to the ensureAnchorHistory function and call it later on in the instantiation process. Maybe when the root app-router is attached ?

[jbuckner]

I was interested in a similar use case and opened #18 which I think will do what you're looking for. It skips any anchor links not handled by the router so if you don't have a catch-all route **, it will allow the browser to handle the routing.