[CodeQuality] Add BareCreateMockAssignToDirectUseRector to phpunit-mock-to-stub set

[TomasVotruba]

Adds BareCreateMockAssignToDirectUseRector to the phpunit-mock-to-stub set.

Inlines a bare createMock() assign directly into the single call that uses it:

 public function test()
 {
-    $someObject = $this->createMock(SomeClass::class);
-    $this->process($someObject);
+    $this->process($this->createMock(SomeClass::class));
 }