Issue #1828528 by dawehner, xjm, tim.plunkett: Add language module integration for views.

core/modules/language/language.views.inc

...rupal/language/Plugin/views/argument/LanguageArgument.php

.../lib/Drupal/language/Plugin/views/field/LanguageField.php

...ib/Drupal/language/Plugin/views/filter/LanguageFilter.php

.../lib/Drupal/views/Tests/Language/ArgumentLanguageTest.php

...ews/lib/Drupal/views/Tests/Language/FieldLanguageTest.php

...ws/lib/Drupal/views/Tests/Language/FilterLanguageTest.php

...iews/lib/Drupal/views/Tests/Language/LanguageTestBase.php

core/modules/views/views.module