[POC][WIP] PIM-3260 : product update api

Propose a way to easily mass update products via an explicit API

 - [ ] support for attribute types
 - [ ] use it in edit common attributes
 - [ ] do we expect the validation inside the updater ? -> first idea, not its concern, should be done in the caller
 - [ ] do we expect the persistence inside the updater ? -> first idea, not its concern, should be done in the caller
 - [ ] specs / behat
 - [ ] technical doc

| Q                    | A
| -------------------- | ---
| Bug fix?             |
| New feature?         |
| BC breaks?           |
| CI currently passes? |
| Tests pass?          |
| Scenarios pass?      |
| Checkstyle issues?*  |
| PMD issues?**        |
| Changelog updated?   |
| Fixed tickets        |
| DB schema updated?   |
| Migration script?    |
| Doc PR               |
should be extracted in another class (validator ?)