Remove the following APIs and export them directly from `dart:ui_web`:
- `urlStrategy` getter and setter
- `HashUrlStrategy`
- `PlatformLocation` and `BrowserPlatformLocation` (keep the façades for non-web platforms)

Depends on https://github.com/flutter/engine/pull/42043
Depends on https://github.com/flutter/engine/pull/42252

Part of https://github.com/flutter/flutter/issues/126831