feat(router): add "paramsInheritanceStrategy" router configuration option

Previously, the router would merge path and matrix params, as well as
data/resolve, with special rules (only merging down when the route has
an empty path, or is component-less). This change adds an extra option
"paramsInheritanceStrategy" which, when set to 'always', makes child
routes unconditionally inherit params from parent routes.

Closes #20572.

packages/router/test/router.spec.ts

@@ -498,7 +498,7 @@ function checkResolveData(
     future: RouterStateSnapshot, curr: RouterStateSnapshot, injector: any, check: any): void {
   const p = new PreActivation(future, curr, injector);
   p.initialize(new ChildrenOutletContexts());
-  p.resolveData().subscribe(check, (e) => { throw e; });
+  p.resolveData('emptyOnly').subscribe(check, (e) => { throw e; });
 }
 
 function checkGuards(