Bidirectional sync to WebDAV

[zhmylove]

Hello! Thanks a lot for your huge work!

Is there any chance you'd make also a bidirectional sync for a webdav provider?

So far it's enabled only for S3:

  private isProviderEnabled(providerName: string): boolean {
    switch (providerName) {
      case 's3':
        return !!(this.settings.s3_bucketName &&
          this.settings.s3_accessKeyId &&
          this.settings.s3_secretAccessKey);
      default:
        return false;
    }
  }

It looks like sync-service already have all the required interfaces: pushToRemote, pullFromRemote, etc. and base-provider also properly handles the webdav backend.

May I ask you, if there is a reason not to add webdav support into isProviderEnabled()?

Maybe I can help you somehow with development?