Support running DWDS without a Chrome Debug Port

[bkonyi]

In certain circumstances we're unable to get access to a Chrome Debug Port to communicate with the Chrome debugger (e.g., when an application is embedded in VSCode, running via the web-server device in Flutter where the application is accessed via a non-Chrome browser) but DWDS support is still needed to provide support for non-debugger related developer tooling (e.g., hot reload, service extension handling).

The DWDS requirement for a Chrome Debug Port should be removed and DWDS should instead provide a limited set of functionality when it doesn't have access to the Chrome debugger.