Fixed: usage of owner side / inversed side on SocialAction / Evaluation

In a ManyToMany relationship, doctrine does take care only of the owning
side of a relationship to inspect changes.

([see
documentation](https://www.doctrine-project.org/projects/doctrine-orm/en/current/reference/unitofwork-associations.html#important-concepts))

This commit mark as "internal" the methods add/removeSocialAction on the
inversed side (`Evaluation`) and let the methods add/removeEvaluation
on the owning side (`SocialAction`) update the inversed side.

The usage is also adapted into SocialWorkMetadata's importer.

src/Bundle/ChillPersonBundle/Entity/SocialWork/SocialAction.php

@@ -112,6 +112,7 @@ class SocialAction
     {
         if (!$this->evaluations->contains($evaluation)) {
             $this->evaluations[] = $evaluation;
+            $evaluation->addSocialAction($this);
         }
 
         return $this;
@@ -310,6 +311,7 @@ class SocialAction
     public function removeEvaluation(Evaluation $evaluation): self
     {
         $this->evaluations->removeElement($evaluation);
+        $evaluation->removeSocialAction($this);
 
         return $this;
     }