Fixes #4454: Improved asset bundle managed and used composer-asset-plugin to manage the dependencies on 3rd-party JS libraries

Fixes #3581: Added `yii\validators\CompareValidator::type` to support type conversion before comparing values

Fixes #5039: `UniqueValidator` and `ExistValidator` did not respect query conditions added by default scope

Fixes #4938: When `yii\db\ActiveQuery` is used to build sub-queries, its WHERE clause is not correctly generated

Fixes #5001: `yii\rest\CreateAction`, `yii\rest\UpdateAction` and `yii\rest\DeleteAction` should throw 500 error if the model operation returns false without validation errors

This fix ensures the format configured in the formatter class is used in the message instead
of the default ICU format.

fixes #4960

Handling $query->joinWith called inside of other $query->joinWith within Closure (called inside Closure). Ex.: ```php $query->joinWith( [ 'rel1' => function($query) { $query->joinWith( [ 'rel2' => function($query) { // ... } ] ); } ] ); ```

This widget usage is not only restricted with `Model` or associative array (see its `normalizeAttributes()` method)