sampling : optimize samplers by reusing bucket sort (#15665)

sampling : optimize samplers by reusing bucket sort (#15665)

* sampling : optimize sorting using bucket sort in more places

ggml-ci

* sampling : do not sort in dist sampler

ggml-ci

* sampling : avoid heap allocations for sort buffers

ggml-ci

* common : add option to sort sampling candidates by probability

ggml-ci

* sampling : revert the change for preserving sort buffers

* sampling : use std::copy instead of memcpy

* sampling : clarify purpose of partial sort helpers

ggml-ci

* cont : remove wrong comment [no ci]

* common : update comment

Co-authored-by: Johannes Gäßler <redacted>
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Co-authored-by: Johannes Gäßler <redacted>