Provide debugging traces and options as a ENV variable or JIT option

🚀 Feature

An environment variable that dumps out the various Thunder provided debug traces to a log file. This can have variable levels like
export THUNDER_DEBUG=<option>

0/'' : Disable
1/'trace' : Enable and dump Thunder generated trace. Can be limited to the trace after delete last used
2/'nvfuser_region' : Enable and dump nvFuser captured regions in addition to 1
3/'nvfuser_code' : Enable and dump nvFuser generated CUDA kernel code in addition to 1 and 2
4/'torch_compile_debug' : Enable the torch.compile debug logging (TORCH_COMPILE_DEBUG=1)

This is a narrow example of the possible debug log levels. Each of these logs can be in a different log file.

Motivation

To get the trace and other debugging information today, we need to add code that captures the trace and prints it after running a model iteration with the inputs.

• This is cumbersome as the training code needs to be edited to enable tracing and re-edited when finished.
• The ability to find when an iteration has finished and add the tracing code at the appropriate location may not always be possible as Thunder aims to compile more and more convoluted set of repositories. For example, when using libraries like
  Lightning Trainer, the user may want to just call model.train() but editing the iteration loop can be difficult.

cc - @mruberry

cc @carmocca @apaz-cli

Start by locating the existing trace capture and printing flow, then review how Thunder, nvFuser, and torch.compile debugging are currently enabled. Define the supported debug levels and log destinations; done should allow tracing from an environment variable or JIT option without editing a training loop.