colabfold metrics sorted by ranking id as string

[tlitfin]

colabfold metrics are currently sorted using rank id as a string. For small numbers of replicates (<10) this doesnt matter but when using increased sampling it leads to ordering like: 1,10,11,12,...,2

[keiran-rowell-unsw]

Ah yep the code should do better on the data types it sorts on.

My preference is with a single point of ranking in sort_structures_by_rank() in utils.py. Or just in /bin frankly if you think it should be promoted 'above' plotting? Then program-specific logic should be easy to expand and find.

[tlitfin]

Closed by #628