Support debugging of SharedWorkers

[auchenberg]

From Customer

Safari on macOS and iOS both have "full support" for SharedWorkers https://developer.mozilla.org/en-US/docs/Web/API/SharedWorker#browser_compatibility and we have an app which uses a SharedWorker but when running in Safari we've yet to find a way to inspect the worker like you would in Chrome with chrome://inspect#workers. Upon further inspection, this was true of Safari dev tools itself and not just Inspect.

[auchenberg]

Marking this as upstream-dependent. Inspect already handles the worker targets that WebKit exposes and maps them to CDP worker targets, but WebKit currently does not expose a debuggable SharedWorker target or deliver SharedWorker debugger messages through the remote inspector. That leaves Inspect with no target or protocol session it can attach to. We will keep this issue as the upstream tracking point and can add the adaptor-side support once WebKit exposes the required target and debugger channel.