`physicalspace(::MultilineMPO, ...)` is not implemented

[leburgel]

There is currently no implementation of physicalspace for MultilineMPO objects it seems. It might be good to add this for consistency, given that it is implemented for MultilineMPS for example:

MPSKit.jl/src/states/multilinemps.jl

Lines 106 to 110 in 97dfaa2

	for f_space in (:physicalspace, :left_virtualspace, :right_virtualspace)
	@eval $f_space(t::MultilineMPS, i::Int, j::Int) = $f_space(t[i], j)
	@eval $f_space(t::MultilineMPS, I::CartesianIndex{2}) = $f_space(t, Tuple(I)...)
	@eval $f_space(t::MultilineMPS) = map(Base.Fix1($f_space, t), eachindex(t))
	end