fix: #3562750 by andres-alvarez: Keep displays when a dependency is removed

Uninstalling a theme, a module or deleting a field deleted every display using its components. Entity view displays and page layouts now drop only the sources depending on what was removed through onDependencyRemoval(), and view displays persist the pruned sources with saveDefaultSources(). Rebased on the current 1.0.x, where sources storage moved to ConfigBuildablePluginBase.