Dependents should not include parents

Problem/Motivation

In #2533844: Use ConfigDependencyManager for determining config dependency we switched to using the ConfigDependencyManager to determine dependent configuration.

The dependency information returned includes graph data: 'paths', which goes up the dependency graph ("What configuration is this piece of configuration dependent on?") and 'reverse_paths', which goes down the dependency graph ("What configuration depends on this configuration?").

Currently we are adding items from 'paths' but we should instead be adding 'reverse_paths' because 'dependents' goes down the graph.

An example of a bug that this problem is producing: When the 'Base type' package assignment plugin is configured to use 'Content type' as a base type, the resulting packages include configuration not specific to the content type. For example, on a site created with the Standard install profile, field storages like field.storage.node.field_tags will be assigned to the first content type package found (article) rather than (under the default package assignment configuration) being assigned to a 'core' package.

Proposed resolution

Use 'reverse_paths' in stead of 'paths'.

Remaining tasks

User interface changes

API changes

Data model changes