File URL's with query string do not get migrated correctly

If the source path for files contains a query string (which is typical when remote images are being migrated), and the destination_file is not specified, the destination filename gets the query string suffixed without all the special characters.

For example, http://example.com/images/large-image.jpg?cb=1 gets saved as large-image.jpgcb1.

The problem is this block of code in \MigrateFileUri::processFile:

    if (empty($this->destinationFile)) {
      $this->destinationFile = basename($this->sourcePath);
    }

The basename function does not strip out the query string from an URL. We have to do that ourselves.

I think it is safe to do this in MigrateFileUri without checking if it is actually a remote URI as ? is not typically a valid character for filenames.