Make members of filters and strategies private

[driehle]

Caution: BC Break

This makes member os filters and strategies private.

For PropertyName filter

The members properties and exclude are now private. As the class itself is marked final, this doesn't have any consequences. No getter/setter methods are provided.

For AbstractCollectionStrategy

The members which are are now private are:

• collectionName -> use setCollectionName() / getCollectionName() instead
• classMetadata -> use setClassMetadata() / getClassMetadata() instead
• object -> use setObject() / getObject() instead
• inflector -> use getInflector() instead, or set inflector using the constructor

While AbstractCollectionStrategy is marked as internal in 3.x, it wasn't internal in 2.x, so this will be a BC break for users upgrading from 2.x who have implemented their own strategies extending from AbstractCollectionStrategy.

[greg0ire]

From https://matthiasnoback.nl/2018/09/assertions-and-assertion-libraries/

User input will indeed be a reason for functions to fail. But so are external failures in outgoing calls. If a function reaches out to the database to fetch an entity by its ID, then the entity may not exist (anymore) and the call will fail. Before you make that call to the database, you don't know yet if the function will fail or not. This is why language designers usually make a difference between LogicExceptions and RuntimeExceptions. They all extend from the generic Exception class, but their intent is different. A RuntimeException is a failure caused by external, unpredictable things: the database, the filesystem, the network, etc. A LogicException is a programming mistake. It shouldn't have happened, but somehow, somewhere, a programmer didn't use a function well.

Suggested change

	throw new RuntimeException('Collection name has not been set.');
	throw new LogicException('Collection name has not been set.');

This also applies below.