[10.x] Added getQualifiedMorphTypeName to MorphToMany (#50153)

It is in addition to qualified names for MorphToMany relations.

src/Illuminate/Database/Eloquent/Relations/MorphToMany.php

@@ -189,6 +189,16 @@ public function getMorphType()
         return $this->morphType;
     }
 
+    /**
+     * Get the fully qualified morph type for the relation.
+     *
+     * @return string
+     */
+    public function getQualifiedMorphTypeName()
+    {
+        return $this->qualifyPivotColumn($this->morphType);
+    }
+
     /**
      * Get the class name of the parent model.
      *