CLOUD: OneDrive storage doesn't work at all

[dwatteau]

This is with either the stable 2.8.x releases, or the current 2.9.0git HEAD, on various devices.

Trying to set up a OneDrive account from scratch in the Cloud tab (with the documented process) always results in a "Saved games sync failed.
Check your Internet connection", although the backend _is_ connected to OneDrive.

The logs don't tell much about what is going on, but running with -d9 gives the following information:

NetworkReadStream: https://graph.microsoft.com/v1.0/drive/special/approot:/saves:/children - Request succeeded
OneDriveTokenRefresher: code = 404
OneDriveTokenRefresher: code = itemNotFound
OneDriveTokenRefresher: message = The resource could not be found.
<irrecoverable> {
  "error":{
    "code":"itemNotFound","innerError":{
      "client-request-id":"XXX-some-uuid-XXX","date":"2024-08-23T12:16:42","request-id":"XXX-some-uuid-XXX"
    },"message":"The resource could not be found."
  }
}
SavesSync::finishError
Storage: error response (failed, 404):
<irrecoverable> {
  "error":{
    "code":"itemNotFound","innerError":{
      "client-request-id":"XXX-some-uuid-XXX","date":"2024-08-23T12:16:42","request-id":"XXX-some-uuid-XXX"
    },"message":"The resource could not be found."
  }
}

Looking a bit at <​https://learn.microsoft.com/en-us/onedrive/developer/rest-api/concepts/special-folders-appfolder?view=odsp-graph-online>, I can't say whether we have proper support for the Files.ReadWrite.AppFolder permission scope that the OneDrive API now appears to require?

I'm making this a blocker, because it looks like current users of the stable releases possibly can't access their ScummVM OneDrive data (saves, settings, games…) anymore, because of this?