[wasm] Switch between threadless and multi-threaded runner

[maraf]

• Switch between threadless and multi-threaded XUnit runner for WASM based on IsThreadless property
• The property will be set in the runtime based on passed flags and based on used runtime flavor
• Mutli-threaded runner extends the runner for other platforms and overrides how results are written (as single line)
• Add current thread id to STRT, PASS and FAIL messages when enabled with XHARNESS_LOG_THREAD_ID

Contributes to dotnet/runtime#88763

[pavelsavara]

Note that the thread ID could be misleading. The task could start on different thread than all the continuations etc ...

[maraf]

Note that the thread ID could be misleading. The task could start on different thread than all the continuations etc ...

I do undestand. When we talked about it few months, you agreed it could be usefull sometimes. I can revert it if you don't se any value in it now

[pavelsavara]

Note that the thread ID could be misleading. The task could start on different thread than all the continuations etc ...

I do undestand. When we talked about it few months, you agreed it could be usefull in sometimes. I can revert it if you don't any value in it now

I learned more since. I don't mind having it behind a flag and occasionally try if it helps to resolve something.