Add "skip_constraints" argument to FeaturesManagerInterface::assignConfigPackage

Follow-up to #2595543: Add "force" argument to FeaturesAssignerInterface::assignConfigPackages()

Problem/Motivation

Currently the 'excluded' constraint on features component packaging is skipped if the $force argument is passed to FeaturesManagerInterface::assignConfigPackage(. The original purpose of $force was to override the restriction that already-assigned configuration won't be reassigned.

However, there are cases including #2596007: Clear out stale excluded and required values where we need finer granularity: the ability to skip constraints without invoking the forcing of reassigning of already-assigned configuration.

Proposed resolution

Add $skip_constraints argument to FeaturesAssignerInterface::assignConfigPackages() and related code as needed and pass to FeaturesManagerInterface::assignConfigPackage(). In 'profile' assignment plugin, skip required constraint if $skip_constraints == TRUE.

Remaining tasks

API changes