Add missing dependencies to multilspy to run Dart LSP in Windows and MacOS

[marcelomendoncasoares]

This is the same content of the PR to multispy to add support to other platforms for Dart LSP.

[MischaPanch]

Thanks! Have you actually tried it with Dart, does the language server work there?

[marcelomendoncasoares]

Thanks! Have you actually tried it with Dart, does the language server work there?

@MischaPanch, I have tried, but with no success to the moment. After the dependencies from this PR, I could start Serena, but all symbol call tools end with the following error:

Error executing tool: 'relativePath'
Traceback (most recent call last):
  File ".../serena/src/serena/agent.py", line 551, in apply_ex
    result = apply_fn(**kwargs)
             ^^^^^^^^^^^^^^^^^^
  File ".../serena/src/serena/agent.py", line 753, in apply
    symbols = self.symbol_manager.find_by_name(
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".../serena/src/serena/symbol.py", line 230, in find_by_name
    symbol_roots = self.lang_server.request_full_symbol_tree(within_relative_path=within_relative_path, include_body=include_body)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".../serena/src/multilspy/language_server.py", line 1780, in request_full_symbol_tree
    ).result(timeout=self.timeout)
      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".../Python/Python311/Lib/concurrent/futures/_base.py", line 456, in result
    return self.__get_result()
           ^^^^^^^^^^^^^^^^^^^
  File ".../Python/Python311/Lib/concurrent/futures/_base.py", line 401, in __get_result
    raise self._exception
  File ".../serena/src/multilspy/language_server.py", line 990, in request_full_symbol_tree
    return await process_directory(start_path)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".../serena/src/multilspy/language_server.py", line 946, in process_directory
    child_symbols = await process_directory(item_path)
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".../serena/src/multilspy/language_server.py", line 946, in process_directory
    child_symbols = await process_directory(item_path)
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".../serena/src/multilspy/language_server.py", line 964, in process_directory
    fix_relative_path(root_nodes)
  File ".../serena/src/multilspy/language_server.py", line 955, in fix_relative_path
    path = Path(node["location"]["relativePath"])
                ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^
KeyError: 'relativePath'

I have not investigated deeper, but I imagine that this is due to Serena not being able to find the symbols, right?