Support for multi-adapter launch

Currently it seems the only way to handle mixed-mode debugging scenarios is to launch with one debugger, hit a breakpoint, and then attach with another debugger. A few examples online:

• Mixed debugging with C++ and Python (example 1)
• Mixed debugging with C++ and Python (example 2)
• Mixed debugging with C++ and C# (example 1)
• Mixed debugging with C++ and C# (example 2)

In Visual Studio we can do a multi-engine launch via IVsDebugger::LaunchDebugTargets where VsDebugTargetInfo::pClsidList can contain CLSIDs for multiple debug engines. In this scenario, the first debug engine is responsible for launching and then the other(s) attach. For an example of this in the Python PTVS tools, see DebugLaunchHelper.cs.

Can something analogous be supported in VS Code? Apart from the launch.json changes, I think main message updates would be requests for launch suspended (or a new field in the Launch request).