Redo changes from field.module to Twig conversion issue that were clobbered

I believe most things were actualy moved into system module.

template_preprocess_field, theme_field, and template_preprocess_field_multiple_value_form was moved into includes/theme.inc
the return array of field_theme was added into drupal_common_theme

field-multiple-value-form.html.twig and field.html.twig was moved into core/system/templates

The only thing I believe stil left to do is that they left field_theme_suggestions_field in field.module, while they created it also on system.module as system_theme_suggestions_field, the attached patch removes it from field.module.

They also removed css from field.module.css, which was moved into system.theme.css

Proposed patch.

Now I see patches are identical except for indices. Re-queuing Manual's original patch for testing.
3: drupal-2226233-2.patch queued for re-testing.

Patch in #6 looks ok and applies cleanly.

Starting to work on that.

That makes total sense Cottser, and thanks ckrina for taking this on!

Attaching the patch.
Anyway, there were still some references to theme_field() and theme_field_multiple_value_form():

• On core/modules/field/field.form.inc
  
  "Callback for usort() within theme_field_multiple_value_form()." > "Callback for usort() within field-multiple-value-form.html.twig."
  
  I've made the change.
• On core/modules/node/node.module, line 705. I'm not sure what to do here, just replace theme_field() by field.html.twig ?
  :
  

  /**
   * Returns HTML for the node title field.
   *
   * This is an override of theme_field() for the node title field. See that
   * function for documentation about its details and overrides.
   *
   * @param array $variables
   *   An associative array. See theme_field() for details.
   *
   * @see theme_field()
   *
   * @ingroup themeable
   */
  function theme_field__node__title($variables) {
    return '<span' . $variables['attributes'] . '>' . drupal_render($variables['items']) . '</span>';
  }
  

_field_sort_items_value_helper() is also used for a usort inside theme_file_widget_multiple() in core/modules/file/file.field.inc. Might be worth adding that in the docblock too, eg "Callback for usort() within field-multiple-value-form.html.twig and theme_file_widget_multiple()."

Thanks @Cottser, I wasn't aware there was a separate cleanup issue.

Patch looks good and applies fine.

$clobbering--;

The only thing that threw me was all those nice docs getting deleted. But basically they're no longer needed, since theming fields now works like theming everything else.

Committed and pushed to 8.x. Thanks!

Do not mix field name and type on one level of template suggestions.
Faced with that in #1962846-8: Use field instance name for header of comment list, drop comment-wrapper template
That leads to field__comment template could be used for for any field that named "comment" for example custom entity with base field named so

Filed follow-up #2229355: Field template suggestions are colliding