Fixes #1162: removed constructors of cache dependency classes so that they can be easily created from configuration.

fixes #1161

[ci skip]

Method 'yii\mail\MailerInterface::compose()' reworked allowing rendering message body.

- 'body()' renamed to 'renderBody()'
- new 'body()' method introduced

Method 'yii\mail\BaseMailer::compose()' updated, allowing composition of the complex methods like 'renderText' and 'body'.