Support attaching to existing process

[DanTup]

The next version of Dart Code will support attaching to an existing VM process (by pasting in an Observatory Uri). It doesn't support all the Flutter functionality (since we don't have a flutter run --machine instance to talk to - I've opened Dart-Code/Dart-Code#905 to figure out what's missing and how we can fix that) but @mit-mit thinks IntelliJ might also not have this so there should be an issue open for it (I can't see an existing one).

[mvarendorff2]

I'm curious about this functionality; has there been any status-updates in the past 6 years / is there any way to contribute to this being made available? I have a personal agenda against VSCode ;)