common: Refactoring sampler parameters (#20429) (#22233)

This change refactors the reasoning_budget_message parameter from the
common params into the sampling parameters specifically. It also removes
the reasoning_budget common parameter and standardizes on the existing
reasoning_budget_tokens parameter in the sampling configuration.

Issue: https://github.com/ggml-org/llama.cpp/issues/20429
Original PR: https://github.com/ggml-org/llama.cpp/pull/20297

common/arg.cpp

@@ -3122,14 +3122,14 @@ common_params_context common_params_parser_init(common_params & params, llama_ex
         "token budget for thinking: -1 for unrestricted, 0 for immediate end, N>0 for token budget (default: -1)",
         [](common_params & params, int value) {
             if (value < -1) { throw std::invalid_argument("invalid value"); }
-            params.reasoning_budget = value;
+            params.sampling.reasoning_budget_tokens = value;
         }
     ).set_examples({LLAMA_EXAMPLE_SERVER, LLAMA_EXAMPLE_COMPLETION, LLAMA_EXAMPLE_CLI}).set_env("LLAMA_ARG_THINK_BUDGET"));
     add_opt(common_arg(
         {"--reasoning-budget-message"}, "MESSAGE",
         "message injected before the end-of-thinking tag when reasoning budget is exhausted (default: none)",
         [](common_params & params, const std::string & value) {
-            params.reasoning_budget_message = value;
+            params.sampling.reasoning_budget_message = value;
         }
     ).set_examples({LLAMA_EXAMPLE_SERVER, LLAMA_EXAMPLE_COMPLETION, LLAMA_EXAMPLE_CLI}).set_env("LLAMA_ARG_THINK_BUDGET_MESSAGE"));
     add_opt(common_arg(