Add a fallback if unable to identify module at line in debugger

[lukaszsamson]

To make it more resilient we can fallback to guessing the module via

:code.all_loaded()
|> Enum.filter(fn {atom, _} -> String.starts_with?(Atom.to_string(atom), "Elixir.") end)
|> Enum.group_by(fn
  {module, path} -> Path.expand(to_string(module.module_info(:compile)[:source]))
end, fn {module, _path} -> module end)

Worst case it will return a list of modules and we may set breakpoints in every one of them