Update info in leading_boundary output for CTMRG

[leburgel]

Addresses #354. Changes the contents of the info named tuple returned by the CTMRG leading_boundary to now include:

• info.converged::Bool: Boolean flag indicating whether or not the leading_boundary run converged to the requested tol within the specified maxiter.
• info.convergence_error::Real: Convergence error after the final iteration of the leading_boundary run.

In addition, I would suggest we remove the intermediate objects used in the contraction algorithm (U/S/V for asymmetric CTMRG, V/D for eigh-C4vCTMRG, Q/R for QR-C4vCTMRG from the output info. This is all extremely specific to the algorithm being used, and as far as I can tell this output is never actually used. I left in the contraction_metrics field, since these metrics do seem useful.

The only place where this output is used is in the info returned by a single ctmrg_iteration (specifically for gauge fixing). That makes much more sense to me, since these decompositions are really intermediate objects in a single iteration. So it makes sense to keep them there. Let me know what you think about removing the decompositions from the info output of leading_boundary @pbrehmer.

[codecov]

Codecov Report

❌ Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/algorithms/ctmrg/ctmrg.jl	80.00%	1 Missing ⚠️

Files with missing lines	Coverage Δ
src/algorithms/ctmrg/ctmrg.jl	90.66% <80.00%> (+0.38%)	⬆️

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[leburgel]

What do you think about removing the decompositions from the info output of leading_boundary @pbrehmer?

[pbrehmer]

Sorry, I somehow missed this review request. I think removing the decompositions from the info output makes a lot of sense. Especially in light of #364, there is no real reason to keep returning the decompositions. I also like the updated docstring, so this is good to go for me.