Constructs a zero-expanded tensor, expanding the leg inner
by sectors as described in zero
.
References syten::STensorImpl::STensor::autodiff_enabled(), syten::STensorImpl::STensor::bi(), syten::STensorImpl::SBasis::gen_basis(), syten::STensorImpl::STensor::rank(), SYTEN_ASSERT_MSG, syten::STensorImpl::STensor::visnz(), and syten::zeroExpand().
Referenced by syten::T3N::TDVP::Worker::project_onto_orthogonal_complement().