The recognizer code used to call Object.freeze() on queryParams before
using them to construct ActivatedRoutes, with the intent being to help
avoid common invalid usage. Unfortunately, Object.freeze() works
in-place, so this was also freezing the queryParams on the actual
UrlTree object, making it more difficult to manipulate UrlTrees in
things like UrlHandlingStrategy.
This change simply shallow-copies the queryParams before freezing them.
Fixes#22617
PR Close#22663
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.
