feat(router): add prioritizedGuardValue operator optimization and allowing UrlTree return from guard (#26478)

* If all guards return `true`, operator returns `true`
* `false` and `UrlTree` are now both valid returns from a guard
* Both these values wait for higher priority guards to resolve
* Highest priority `false` or `UrlTree` value will be returned

PR Close #26478

packages/router/test/BUILD.bazel

@@ -16,6 +16,7 @@ ts_library(
         "//packages/router/testing",
         "@rxjs",
         "@rxjs//operators",
+        "@rxjs//testing",
     ],
 )