Pull "Open Ports" feature out into main DevTools

In the VM developer tools page, there is a feature to debug open ports (`VM Tools --> Isolates --> Open Ports`). This is useful for the general developer, not just the VM developer. For example, debugging why a test won't terminate. Here's a request for this feature that we've closed, although access to the feature requires the user to know that "VM developer mode" must be enabled: https://github.com/flutter/devtools/issues/844.

One question is where this feature would live. A related request is for a tool in DevTools to track leaking async operations (https://github.com/flutter/devtools/issues/5581) - maybe these two features are related and could live in a similar location?

Beginne mit der Untersuchung der Seite zu den VM developer tools und der vorhandenen Funktion VM Tools \u001a Isolates \u001a Open Ports. Lies die Issues 844 und 5581, um den bisherigen Kontext zu verstehen und festzustellen, ob das Tool async-leak die Platzierung beeinflusst. Als abgeschlossen gilt die Aufgabe, wenn die Funktion open-ports in main DevTools verfügbar ist, ohne den VM developer mode zu erfordern.

Vom Indexierungsmodell aus dem Issue-Text verfasst.