seqkit: switch to sample2 subcommand

[bounlu]

Switched to sample2 for a more accurate and memory efficient option: https://bioinf.shenwei.me/seqkit/usage/#sample2

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[jfy133]

@bounlu I think this should instead be a separate module - it's an entirely new subcommand, and maybe have slightly different output (based on the description). IOt oculd be people are theoretically reliant on the original implementation, so that should stay as is.

This would be a relatively easy module to do though, you just copy over the existing module just adding 2 to every reference of teh sample subcommand/name

[mashehu]

then this module needs to be called seqkit/sample2, i.e. a new module needs to be created for this