Replace instances of drupal_sort_weight with SortArray::sortWeight

Problem/motivation

When #2028499: drupal_sort_weight should be converted to a class goes in, then drupal_sort_weight will be deprecated.

Proposed resolution

Replace all instances of
uasort($operations, 'drupal_sort_weight');
with
uasort($operations, array('Drupal\Component\Utility\SortArray', 'sortWeight'));