Adopt formatOnSave changes

[jrieken]

Since VS Code now has the editor.formatOnSave-setting and the onWillSaveTextDocument-event, this code should be revisited. I'd recommend to remove it and to rely on the built-in formatOnSave feature or to use the new event. Both will prevent unnecessary fs-operations and reduce the risk for endless write-event-write loops.

See https://code.visualstudio.com/updates#_format-on-save, microsoft/vscode#12449, and microsoft/vscode#239 for more details

[Lonefy]

Done

[jrieken]

Thanks