llama : refactor sampling_info to use buffer_view template (#19368)

* llama : refactor sampling_info to use buffer_view template

This commit updates the sampling_info struct in llama-context to use a
buffer_view template for the logits, probs, sampled tokens, and
candidates buffers.

The motivation for this is to simplify the code, improve type safety
and readability.

src/llama-context.h

@@ -4,6 +4,7 @@
 #include "llama-cparams.h"
 #include "llama-graph.h"
 #include "llama-adapter.h"
+#include "llama-impl.h"
 
 #include "ggml-cpp.h"
 #include "ggml-opt.h"
@@ -269,29 +270,19 @@ private:
     std::unique_ptr<llama_memory_i> memory;
 
     // decode output (2-dimensional array: [n_outputs][n_vocab])
-    size_t  logits_size = 0; // capacity (of floats) for logits
-    float * logits      = nullptr;
+    struct buffer_view<float>  logits = {nullptr, 0};
 
     // embeddings output (2-dimensional array: [n_outputs][n_embd])
     // populated only when pooling_type == LLAMA_POOLING_TYPE_NONE
-    size_t  embd_size = 0; // capacity (of floats) for embeddings
-    float * embd      = nullptr;
+    struct buffer_view<float>  embd = {nullptr, 0};
 
-    // TODO: simplify
     struct sampling_info {
         std::map<llama_seq_id, llama_sampler *> samplers;
 
-        float       * logits      = nullptr;
-        size_t        logits_size = 0;
-
-        llama_token * sampled      = nullptr;
-        size_t        sampled_size = 0;
-
-        float       * probs        = nullptr;
-        size_t        probs_size   = 0;
-
-        llama_token * candidates   = nullptr;
-        size_t        candidates_size = 0;
+        struct buffer_view<float>       logits     = {nullptr, 0};
+        struct buffer_view<llama_token> sampled    = {nullptr, 0};
+        struct buffer_view<float>       probs      = {nullptr, 0};
+        struct buffer_view<llama_token> candidates = {nullptr, 0};
 
         std::vector<uint32_t> logits_count;
         std::vector<uint32_t> probs_count;