Add Hint Index in queries

I need force index in my project, so I've add the method addHintIndex to set the hints indexes associated to a table.
The param is an assoc array of the hintIndex(s) to be used on the query.
The key is the name of the table to be hinted.
The value is the hint settings or an array of hints settings to apply.
Each hint setting is compose by one to three string values defining the hint and one array defining the index(s) to hint.

Here are some examples:

$query = (new \yii\db\Query())->from(['t' => 'user'])->addHintIndex(['user' => [
    ['force', 'index', ['primary']],
    ['ignore', 'index', 'order by', ['i1']],
]])->leftJoin('profile as p', 'user.id = profile.user_id')->addHintIndex(['profile' => [
    'use', 'index', ['i2']
]]);

// sql -> SELECT * FROM `user` `t` FORCE INDEX (primary) IGNORE INDEX FOR ORDER BY (i1)
 LEFT JOIN `profile` `p` ON user.id = profile.user_id USE INDEX (i2)

$users = User::find()->addHintIndex(['user' => [['use', 'index', ['primary']]]])->one();

// sql -> SELECT * FROM {{%user}} USE INDEX (primary)

I have no experience enought with other drivers than mysql, so just write functionality for mysql and sqlite drivers (the former tested the last pending for testing).

Driver overwritting can be done on:

• /yii2/framework/db/mysql/QueryBuilder.php
• /yii2/framework/db/sqlite/QueryBuilder.php (require testing)*
• /yii2/framework/db/cubrid/QueryBuilder.php (trace a message and ignore addHintIndex)*
• /yii2/framework/db/mssql/QueryBuilder.php (trace a message and ignore addHintIndex)*
• /yii2/framework/db/oci/QueryBuilder.php (trace a message and ignore addHintIndex)*
• /yii2/framework/db/pgsql/QueryBuilder.php (trace a message and ignore addHintIndex)*

Start by reading framework/db/mysql/QueryBuilder.php and framework/db/sqlite/QueryBuilder.php, then trace how Query builds table and join SQL. Check the corresponding driver QueryBuilder entry points listed in the issue; done means addHintIndex is handled for MySQL and SQLite and safely ignored with a trace message by the other listed drivers.