Regression: "excluded" configuration should not be automatically packaged

Problem/Motivation

This is a recurrence of #2595245: "excluded" configuration should not be automatically packaged.

From that issue:

When an admin manually edits a feature and removes a configuration item, that item is designated as "excluded". When an admin subsequently edits the feature, the item will show up as automatically detected (blue) but will not be checked by default. This is working as expected.

However, when a set of features is regenerated, the "excluded" flag is ignored; configuration is assigned to the feature whether or not it has been previously flagged as "excluded".

The expected behaviour is that any configuration marked as excluded will not be assigned to the given feature when the feature set is regenerated.

In a related bug, when a given feature is exported via Drush, the "excluded" flag is also ignored.

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes