SolvedDart Code Implement refactor: Move file

Blocked on microsoft/vscode#43768 being finalised.

Update: The VS Code API works, however despite supporting multiple files, it is only ever fired once-per-file https://github.com/microsoft/vscode/blob/926fc23f139e4d1250dba494c6e825e4816e62f6/src/vs/workbench/api/common/extHostFileSystemEventService.ts#L148 concurrently. This results in multiple MOVE_FILE calls to the analysis server, which currently only supports one refactor at a time (a new refactor cancels the previous).

The implement this reasonably (and without causing a potentially-large number of sequential requests to the server) we need to either have the server support multiple files, or do more work on the server (eg. via LSP).

The work is mostly done here, but it requires a VS Code feature that is currently part of the provisional API. In order to ship this, we need it to be moved to the stable API.

The relevant issue is microsoft/vscode#43768. I'll ping again to see if there's any update.

Ok, going to ship this behind a flag for vNext (dart.previewUpdateImportsOnRename):

It only works for single-files and no folders, but that's probably better than nothing. When the VS Code issue is fixed, I think we can support multiple files, though it may be slow for large numbers (due to lots of round trips to the server). Supporting multiple files quickly and/or folders will probably be best done in the server along with LSP once it gets the API.

I've opened some extra issues to track the other work:

• #2482 - remove preview flag
• #2483 - support multiple files

There's a beta build here if you'd like to try it out:

https://github.com/Dart-Code/Dart-Code/releases/tag/v3.11.0-beta.3

Download the .vsix file, then run Extensions: Install from VSIX from the VS Code command palette and select the file.

Then set "dart.previewUpdateImportsOnRename": true in your VS Code settings and restart.

If you have VS Code set to auto-update extensions, when this version is released stable, you'll automatically be updated, so you don't need to worry about uninstalling (unless something is broken - but please file issues if it is!).

Sorry, the work on this somewhat stalled due to other priorities and not many people asking for this. I think the work in the server supports renaming files, just not folders. It might be possible to wire just that bit up - I'll try and take a look soon.