tool: add undocumented option --dump-module-paths for win32

- Add an undocumented diagnostic option for Windows to show the full
  paths of all loaded modules regardless of whether or not libcurl
  initialization succeeds.

This is needed so that in the CI we can get a list of all DLL
dependencies after initialization (when they're most likely to have
finished loading) and then package them as artifacts so that a
functioning build can be downloaded. Also I imagine it may have some use
as a diagnostic for help requests.

Ref: https://github.com/curl/curl/pull/3103

Closes https://github.com/curl/curl/pull/3208