- Some bugfixes made in Relation

- Fixed search() methods in EntityCollection
- Work done on Relations of EntityTrait ; a lot of work still to be done. It must also move to another file.

src/Annotation/Property/Relation.php

@@ -6,17 +6,17 @@ class Relation implements \Ulmus\Annotation\Annotation {
 
     public string $type;
 
-    public string $key;
+    public /*stringable*/ $key;
 
-    public string $foreignKey;
+    public /*stringable*/ $foreignKey;
 
     public array $foreignKeys;
 
     public string $bridge;
 
-    public string $bridgeKey;
+    public /*stringable*/ $bridgeKey;
 
-    public string $bridgeForeignKey;
+    public /*stringable*/ $bridgeForeignKey;
     
     public string $entity;