Allow to change the endpoint option to the uploadItem

[wil92]

I'm using the library in a system where the files can be uploaded to more than one endpoint, and is a little bit difficult to change the endpoint for different files, because is not nice to change the service configuration each time i need to upload a file (that what i'm doing now):

1. define autoUpload as false

options: UploadxOptions = {
    concurrency: 2,
    autoUpload: false,
    chunkSize: 1024 * 256 * 8
  };

2. this.uploadxService.handleFile(file); // Put the file ready to upload
3. subscribe and start upload the file

let itemId = null;
return this.uploadsProgress.pipe(
      map((item: UploadState) => {
        if (!itemId && item.status === 'added') {
          itemId = item.uploadId;
          this.uploadxService.control({
            action: 'upload',
            itemOptions: {
              token: 'toekneeeeeeeeeee',
              uploadId: itemId,
              endpoint: apiEndpoint,
              method: 'POST'
            } as UploadItem
          } as UploadxControlEvent);
        }
        return item;
      }),
      filter((item: UploadState) => item.status === 'cancelled' || item.status === 'complete' || item.status === 'error' && item.uploadId === itemId)
    );

this should work but the endpoint is not updated in the configure method in Uploader class:

configure(item = {} as UploadItem): void {
    const { metadata, headers, token } = item;
    this.metadata = {
      name: this.name,
      mimeType: this.mimeType,
      size: this.size,
      ...unfunc(metadata || this.metadata, this.file)
    };
    this.chunkSize = this.options.chunkSize || this.chunkSize;
    this.maxRetryAttempts = this.options.maxRetryAttempts || this.maxRetryAttempts;
    this.refreshToken(token);
    this.headers = { ...this.headers, ...unfunc(headers, this.file) };
  }

Other idea is to return the uploader in the handler method because right now i need to take the uploaderId in the uploadsProgress as an even of the service.