Allow for non-square / uniform MPOHamiltonians in make_time_mpo(..., ::TaylorCluster)

[VictorVanthilt]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 89.69072% with 20 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/algorithms/timestep/wii.jl	62.96%	20 Missing ⚠️

Files with missing lines	Coverage Δ
src/MPSKit.jl	100.00% <ø> (ø)
src/algorithms/timestep/taylorcluster.jl	100.00% <100.00%> (ø)
src/algorithms/timestep/time_evolve.jl	100.00% <ø> (ø)
src/operators/abstractmpo.jl	57.14% <100.00%> (+1.21%)	⬆️
src/operators/mpohamiltonian.jl	88.95% <100.00%> (ø)
src/algorithms/timestep/wii.jl	62.96% <62.96%> (ø)

... and 4 files with indirect coverage changes

[lkdvos]

I made an attempt at fixing this, I have something that seems to be running, and at least locally produces the correct scaling behavior. Comparing the 2nd order infinite result though, it seems like we obtain a 6x6 matrix for a nearest-neighbour model, which does not match the 3x3 that the paper shows (appendix A).
Honestly, I would love to just write down and compare to these exact expressions as a testcase, I also don't think the tests you added are working...