sampling : Integrate Top-nσ into main sampling chain (and add it to the server) ...

sampling : Integrate Top-nσ into main sampling chain (and add it to the server) (#13264)

* sampling: add Top-nσ sampler to `llama-server` and sampler ordering

* revert: sampler ordering

* revert: VS' crappy auto-formatting

* revert: VS' crappy auto-formatting pt.2

* revert: my crappy eye sight...

* sampling: add XTC to Top-nσ sampler chain

* sampling: add Dyna. Temp. to Top-nσ sampler chain

* sampling: actually remove Top-nσ from sampler(oops)

* Integrate top_n_sigma into main sampler chain

* Define COMMON_SAMPLER_TYPE_TOP_N_SIGMA

* Formatting

* Lint

* Exit early in the sampler if nsigma < 0

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Co-authored-by: CasualAutopsy <redacted>