Fix case of interface name (#2997)

And baseline phpstan error due to non-inherited parameter type

phpstan-baseline.neon

@@ -30,6 +30,12 @@ parameters:
 			count: 1
 			path: src/Aggregation/Builder.php
 
+		-
+			message: '#^Method Doctrine\\ODM\\MongoDB\\Aggregation\\Expr\:\:mergeObjects\(\) has parameter \$expressions with no type specified\.$#'
+			identifier: missingType.parameter
+			count: 1
+			path: src/Aggregation/Expr.php
+
 		-
 			message: '#^Method Doctrine\\ODM\\MongoDB\\Aggregation\\Stage\:\:execute\(\) return type with generic interface Doctrine\\ODM\\MongoDB\\Iterator\\Iterator does not specify its types\: TValue$#'
 			identifier: missingType.generics

src/DocumentManager.php

@@ -255,7 +255,7 @@ class DocumentManager implements ObjectManager
     }
 
     /** Gets the metadata factory used to gather the metadata of classes. */
-    public function getMetadataFactory(): ClassmetadataFactoryInterface
+    public function getMetadataFactory(): ClassMetadataFactoryInterface
     {
         return $this->metadataFactory;
     }