collection.Base#filter() should use constructor for allItems

In Neo.collection.Base#filter(), the allItems collection was previously hardcoded to be created as a Neo.collection.Collection instance.

This caused issues for subclasses like Neo.data.Store, where the allItems collection would lose the store's specific functionalities, such as lazy record instantiation via the get() method.

The fix is to use me.constructor instead of Collection when creating the allItems instance. This ensures that allItems is an instance of the same class as the collection being filtered, preserving the subclass's methods and behaviors.

This change is crucial for components like Neo.form.field.ComboBox that rely on stores and their filtering capabilities.