content_translation should add views translation link field

Problem/Motivation

In NodeViewsData

    if (\Drupal::moduleHandler()->moduleExists('content_translation')) {
      $data['node']['translation_link'] = array(
        'title' => t('Translation link'),
        'help' => t('Provide a link to the translations overview for nodes.'),
        'field' => array(
          'id' => 'content_translation_link',
        ),
      );
    }

and now in #1984582: Add views support for custom blocks

    if ($this->moduleHandler->moduleExists('content_translation')) {
      $data['block_content']['translation_link'] = array(
        'title' => $this->t('Translation link'),
        'help' => $this->t('Provide a link to the translations overview for custom blocks.'),
        'field' => array(
          'id' => 'content_translation_link',
        ),
      );
    }

Proposed resolution

We can move this to content_translation

Remaining tasks

Create patch

User interface changes

None

API changes

Simple code moment so none.