Refactor PDF signature handling and add signature state changer

Simplified PdfSignedMessageHandler by delegating signature state changes to a new SignatureStepStateChanger class. Added utility method to EntityWorkflowStepSignature for checking pending signatures and created new test cases for the SignatureStepStateChanger.

src/Bundle/ChillMainBundle/Entity/Workflow/EntityWorkflowStepSignature.php

@@ -141,6 +141,32 @@ class EntityWorkflowStepSignature implements TrackCreationInterface, TrackUpdate
         return EntityWorkflowSignatureStateEnum::SIGNED == $this->getState();
     }
 
+    public function isPending(): bool
+    {
+        return EntityWorkflowSignatureStateEnum::PENDING == $this->getState();
+    }
+
+    /**
+     * Checks whether all signatures associated with a given workflow step are not pending.
+     *
+     * Iterates over each signature in the provided workflow step, and returns false if any signature
+     * is found to be pending. If all signatures are not pending, returns true.
+     *
+     * @param EntityWorkflowStep $step the workflow step whose signatures are to be checked
+     *
+     * @return bool true if all signatures are not pending, false otherwise
+     */
+    public static function isAllSignatureNotPendingForStep(EntityWorkflowStep $step): bool
+    {
+        foreach ($step->getSignatures() as $signature) {
+            if ($signature->isPending()) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
     /**
      * @return 'person'|'user'
      */