Language server expected behavior

[jourdain]

editor = code.Editor(
  # ...
  lang_config=Path("./lang.yaml"), # Multi instance pointing to same file should reuse the same manager
)
editor.get_language_server_manager() # return instance of lang_server helper
editor.stop_all_language_servers() # ensure all language server stop and close all of their processes.

The YAML should contain the language server command line but also maybe other config information for the client.

Technically, we should support either YAML and JSON.

The lang_server helper should have API like (not limited to):

• supported_languages (@Property) => [str, ...]
• running
• start()
• stop()
• get_language_config(name)
• config_path => str (abs path)
• client_config (@Property)