Renaming MPSMultiline and MPOMultiline to MultilineMPS and MultilineMPO

[VictorVanthilt]

This PR replaces every occurrence of MPSMultiline with MultilineMPS.
Now all MPSKit state and operator names follow the {attribute}{type} format (e.g. FiniteMPS, InfiniteQP, FiniteMPOHamiltonian, ...).

[codecov]

Codecov Report

Attention: Patch coverage is 71.57895% with 27 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/operators/multilinempo.jl	35.00%	13 Missing ⚠️
src/states/multilinemps.jl	70.58%	5 Missing ⚠️
...c/algorithms/excitation/quasiparticleexcitation.jl	62.50%	3 Missing ⚠️
src/algorithms/changebonds/svdcut.jl	33.33%	2 Missing ⚠️
src/algorithms/derivatives.jl	66.66%	2 Missing ⚠️
src/algorithms/expval.jl	66.66%	1 Missing ⚠️
src/environments/infinitempo_envs.jl	90.00%	1 Missing ⚠️

Files with missing lines	Coverage Δ
src/MPSKit.jl	100.00% <ø> (ø)
src/algorithms/approximate/idmrg.jl	97.67% <100.00%> (ø)
src/algorithms/approximate/vomps.jl	72.72% <100.00%> (ø)
src/algorithms/changebonds/changebonds.jl	100.00% <100.00%> (ø)
src/algorithms/changebonds/optimalexpand.jl	100.00% <100.00%> (ø)
src/algorithms/changebonds/randexpand.jl	100.00% <100.00%> (ø)
src/algorithms/grassmann.jl	99.14% <100.00%> (-0.86%)	⬇️
src/algorithms/statmech/gradient_grassmann.jl	100.00% <100.00%> (ø)
src/algorithms/statmech/vomps.jl	72.72% <100.00%> (ø)
src/algorithms/statmech/vumps.jl	72.00% <100.00%> (ø)
... and 12 more

... and 1 file with indirect coverage changes