feat: POC support relative problem path when inside a VSCode workspace

[dqhieuu]

Why: I use git to store my code files across machines with different OSes, and since the problem paths are absolute, they don't work between machines.

Main points:

• Use workspace root as the relative root
• Remove srcPath entirely, encode the entire path in the file name. Path ./a/b/c/file.cpp becomes file name a$$b$$c$$file.cpp. Pros:
  • O(1) lookup
  • Doesn't need to deserialize JSON to find the file name
  • Easy to update the path when the code file is moved/renamed.