Issue #2002274 by elvis2: Rename Views method add_relationship() to addRelationship().

.../Drupal/comment/Plugin/views/field/NcsLastCommentName.php

...b/Drupal/comment/Plugin/views/sort/NcsLastCommentName.php

.../Drupal/field/Plugin/views/relationship/EntityReverse.php

...search/lib/Drupal/search/Plugin/views/argument/Search.php

...s/search/lib/Drupal/search/Plugin/views/filter/Search.php

...rupal/taxonomy/Plugin/views/relationship/NodeTermData.php

core/modules/views/lib/Drupal/views/ManyToOneHelper.php

...modules/views/lib/Drupal/views/Plugin/views/query/Sql.php

...b/Drupal/views/Plugin/views/relationship/GroupwiseMax.php

...iews/Plugin/views/relationship/RelationshipPluginBase.php