Get a view of the orthogonality center of an MPS/MPO

I think it would be useful, based on discussions in ITensor/ITensors.jl#515, to be able to easily get views of the orthogonality center of an MPS/MPO. This would allow someone to just scale the orthogonality centers of an MPS/MPO (if it is a range), for example. It could be syntax like:

psi[ortho_lims(psi)] .*= 2

Here, ortho_lims(psi) could output a range of the orthogonality center, so 1:N if there is no orthogonality and 4:5 if the left limit is 3 and the right limit is 6. We could come up with a different name, since there is an off-by-one convention discrepancy with ITensors.leftlim and ITensors.rightlim (and honestly, I always get confused by the convention used in those functions, and would be open to switching them).