EnforceReadonlyPublicPropertyRule: support asymmetric visibility

Do not report publicPropertyNotReadonly error when property uses
private(set) or protected(set) modifiers, as these properties are
effectively readonly from outside the class.

Fixes #319

Author: JanTvrdik

src/Rule/EnforceReadonlyPublicPropertyRule.php

@@ -41,7 +41,7 @@ public function processNode(
             return [];
         }
 
-        if (!$node->isPublic() || $node->isReadOnly() || $node->hasHooks()) {
+        if (!$node->isPublic() || $node->isReadOnly() || $node->hasHooks() || $node->isPrivateSet() || $node->isProtectedSet()) {
             return [];
         }
 

tests/Rule/data/EnforceReadonlyPublicPropertyRule/code-84.php

@@ -57,3 +57,9 @@ class ImplementingClass implements MyInterface {
 class ImplementingClass2 implements MyInterface {
     public readonly string $key;
 }
+
+class AsymmetricVisibility {
+    public private(set) string $privateSet;
+    public protected(set) string $protectedSet;
+    public public(set) string $publicSet; // error: Public property `publicSet` not marked as readonly.
+}