WASM: Fix System.Net.Primitives and tests (#39748)
Add HostInformationPal and InterfaceInfoPal implementations for Browser.
In CookiePortTest.cs use example.com instead of localhost for the tests since Browser uses `localhost` as the `Environment.MachineName` and that changes the test values.
Allows the tests to run on WebAssembly:
```
System.Net.Primitives.Pal.Tests: Tests run: 60, Errors: 0, Failures: 0, Skipped: 0. Time: 0.15872s
System.Net.Primitives.Functional.Tests: Tests run: 2620, Errors: 0, Failures: 0, Skipped: 1. Time: 3.145804s
```