Decouple DS debug adapter tracker for the python tracker

[karthiknadig]

VSCode allows one DebugAdapterTracker per language. Currently DS registers an debug adapter tracker named debugLocationTracker. This tracker run is the non-DS scenarios and is currently designed to be a singleton instance.

DebugAdapterTracker should be created for each debug session since there can be multiple debug sessions. The DS debugLocationTracker overwrites the debug session field in it every time a new session is created. This is creates issues when tracking multi process scenarios where there can be multiple debug sessions.

We need a common tracker that can handle singleton instances as needed by DS and per session instances as needed by debug session telemetry

[rchiodo]

@karthiknadig is this breaking multi process scenarios now?

[karthiknadig]

Yes.

1. For extension, it results in telemetry not being accurate in multi process scenarios.

2. For DataScience, this is a problem when multiproc or multiple threads are used. Suppose you have a debug session running. If the code that user is currently debugging spawns another process. A new concurrent debug session will start, now when a breakpoint, exception, is hit. The code inside DebugLocationTracker.getStackTrace may not get the right stack. Since the same tracker is used. That code is currently broken for multi-thread case as well, since the actual location might be different for each thread.

[greazer]

Validate that multiproc debugging works for regular python AND we still support debugging in the interactive window.

The rest we can do later.

[IanMatthewHuff]

Validated. Did a quick check to see if the debug location moved to the correct location while debugging some cells with function calls.