Create SelectInterface::leftInnerJoin() and SelectInterface::leftOuterJoin() and make them fluent.

Problem/Motivation

Currently we have in the SelectInterface the following methods: join(), innerJoin(), leftJoin() and rightJoin(). They are non-fluent and that makes creating queries with them less beautiful and less readable. So, from:

  $query = db_select('node', 'n')
    ->fields('n', array('nid'))
    ->condition('n.language', $langcode);
  $query->join('field_data_field_home_code', 'hc', 'hc.entity_id = n.nid);
  $nids = $query
    ->condition('hc.field_home_code_value', $house_code)
    ->execute()
    ->fetchCol();

To:

  $nids = db_select('node', 'n')
    ->fields('n', array('nid'))
    ->condition('n.language', $langcode);
    ->join('field_data_field_home_code', 'hc', 'hc.entity_id = n.nid);
    ->condition('hc.field_home_code_value', $house_code)
    ->execute()
    ->fetchCol();

Proposed resolution

1. The two new methods need to be added to the Drupal\Core\Database\Query\SelectInterface (leftInnerJoin() and leftOuterJoin()). The return value will become $this.
2. Implement the two new methods in the class Drupal\Core\Database\Query\Select. Use the method addJoin to create their functionality and the return value will be $this.
3. The two new methods need testing. Use Drupal\KernelTests\Core\Database\SelectComplexTest::testDefaultJoin() and Drupal\KernelTests\Core\Database\SelectComplexTest::testLeftOuterJoin() as examples and create two new tests (testLeftInnerJoinFluent() and testLeftOuterJoinFluent()).
4. Deprecate the methods join(), innerJoin() and leftJoin() on the Drupal\Core\Database\Query\SelectInterface. The method rightJoin() does not need to be deprecated, because it is already deprecated.
5. Remove the usages of the methods join(), innerJoin() and leftJoin() in the rest of Drupal core. If the join alias is needed then use the method addJoin(). If he join alias is not needed use the method leftInnerJoin() or leftOuterJoin().

Remaining tasks

1. Write patch
2. Review patch
3. Create a change record

User interface changes

None.

API changes

Yes. Two methods are added to Drupal\Core\Database\Query\SelectInterface (leftInnerJoin() and leftOuterJoin()). Three methods are deprecated on Drupal\Core\Database\Query\SelectInterface (join(), innerJoin(), leftJoin()).

Data model changes

None.