Provide a flag indicating when a command as been invoked manually or automatically, to allow for better error responses

My servers currently returns an error if you invoke the Organize Imports command on a file that has parse errors. However if I add this command to editor.codeActionsOnSave in VS Code, this means anytime I press Save with an invalid file, I get a notification that the Organize Imports call fails.

If I change my server to return silently in this case (which we currently do for formatting), then if a user manually invokes the command, it would silently do nothing (perhaps due to an error that's not visible on-screen) and might seem like the command is not working.

It would be nice if we could tell when a command was triggered automatically so we can suppress the error response (or, if there were some guidelines to IDEs to do this automatically).

Start with the Language Server Protocol command behavior and the VS Code codeActionsOnSave scenario described in the issue. Since no file or test is named, trace the protocol specification and existing command-related tests; done means an agreed way to distinguish automatic from manual invocation.