Add method batchUpdate in \yii\db\QueryBuilder

Very often in practice I have to do a bulk update of rows.

IN PostgreSQL:

UPDATE table AS t
SET
    col1 = c.col1,
    col2 = c.col2
FROM (VALUES (1, 1, 1), (2, 2, 2), (3, 3, 3), (4, 4, 4) ) AS c (id, col1, col2)
WHERE c.id = t.id;

or

INSERT INTO table (id, col1, col2) 
      VALUES (1, 1, 1), (2, 2, 2), (3, 3, 3), (4, 4, 4)
ON CONFLICT (id) DO UPDATE SET 
  col1 = EXCLUDED.col1,
  col2 = EXCLUDED.col2

IN MySQL:

INSERT INTO table (id, col1, col2)
     VALUES (1, 1, 1), (2, 2, 2), (3, 3, 3), (4, 4, 4)
ON DUPLICATE KEY UPDATE
    col1 = VALUES(col1),
    col2 = VALUES(col2);

I'm sure other databases have similar capabilities.
For each DBMS will have its own specific implementation of the method batchUpdate in descendant classes.

Sorry for my bad english.

Start with the \yii\db\QueryBuilder entry point and inspect its descendant classes for database-specific implementations. Compare the PostgreSQL and MySQL SQL examples in the issue, then define the shared batchUpdate API and determine how each DBMS implementation should be validated.