Fix EZP-21584: Field types do not normalize sortKey properly

This PR resolves issue https://jira.ez.no/browse/EZP-21584

#### Problem

sortKey strings need to be normalized (downcased) before being stored. This needs to be done in field type implementations, as this is the place where API field value is converter to Persistence value. For this (string) TransformationProcessor component exists, but is located in the Legacy Storage.

#### Resolution
* Transformation processor is moved to `eZ\Publish\Core\Persistence\TransformationProcessor`, to be used in any storage as needed and also higher in `eZ\Publish\Core\FieldType`
* base field type class gets new dependency to TransformationProcessor, therefore it is available to all field type extending it

#### Additional
* RelationList does not provide sort info (in Legacy, in future this might change but needs to be defined)
* Rating Value does not cast it's argument. This means validation will throw an InvalidArgumentType exception if non-boolean is given
* various small cleanups: PHPDoc, unnecessary imports, deprecated TODOs, configurations and dependencies in tests