Populate Profiling and Debugging doc

[GregoryComer]

📚 The doc issue

Note: This issue pertains to the executorch-just-works branch. It is intended to merge back into master within the next 1-2 weeks.

Fill out the top-level profiling and debugging doc page under using-executorch-troubleshooting.md. This page should serve as an introduction to devtools and general troubleshooting flow. Provide guidance and links to deeper docs on profiling and model optimization.

General documentation guidelines that I'm hoping to follow:

• Leverage brief in-line code samples, where possible
• Keep things concise
• Avoid first person (I/we)
• I'm generally trying to follow https://developers.google.com/style/highlights

Suggest a potential alternative/fix

No response

cc @mergennachin @byjlw