DI token carrying the factory that every cngx feature uses to
allocate its commit controller. Default providedIn: 'root'
factory returns createCommitController. Override globally
via app providers or per-component via viewProviders.
Symmetrical to CNGX_SELECT_COMMIT_CONTROLLER_FACTORY
(@cngx/forms/select); the select-side token's default factory
delegates to this one, so a single override here cascades into
every select variant transparently.