Test: debug threads

[isidorn]

• win @kieferrm
• mac @jrieken
• linux @joaomoreno

We have changed quite some things how threads are handled by the vscode debugger. Pick one language that supports multiple threads (e.g go, c++, mono, php) and verify:

• Newly created threads are reflected in the callStack view
• Multiple threads can be stopped at the same time and it is possible to inspect their call stack
• One thread resuming execution does not affect other stopped threads

[felixfbecker]

• A thread that exits should disappear from the call stack view