Extend debug_create_symbol_lookup_context().

- debug_create_symbol_lookup_context() now takes an image ID
  parameter that can optionally be used to restrict the symbols
  it gathers to only those of the targeted image rather than the
  entire team, allowing for significantly more lightweight usage
  when the desired image is known. The previous behavior can still
  be obtained if desired by passing -1 as said ID.

- Adjust callers.