asArray will not include null valued keys

fixes #1311

[ci skip]

fixes #4086

fixes #4012

yii\redis\ActiveRecord::deleteAll() refactoring - no need to write to socket 2 times when nothing found

yii\redis\ActiveRecord::deleteAll() refactoring - no need to write to socket 2 times when nothing found

[ci skip]

```
vendor/bin/indent --spaces -r framework/
vendor/bin/indent --tabs -r . --pattern=*.json
vendor/bin/indent --spaces -r . --pattern=*.md
vendor/bin/indent --spaces -r . --pattern=yii.*.js
vendor/bin/indent --spaces -r . --pattern=*.css
```

Fixes #2955: Changed the signature of ActiveQuery constructors and `ActiveRecord::createQuery()` to simplify customizing ActiveQuery classes

so information about changed values is available in `afterSave`-event.

fixes #2892