Bug 403232: allow re-use of existing locator while still allowing for it to be reclaimed if no-one is using it
Bug 403232: remove static Sisu helper out of base bundle as it has potential to lead to leaks via the thread-local pool (will move this to a separate helper bundle and rework it)
Bug 393214: only consider ACTIVE bundles when building injectors, ignore STARTING bundles (includes lazy-activation) for now unless we have a definite need - otherwise we could get overlapping activation events that could lead to duplicate injectors being created (will address this in another commit)