tests: allow exporting graph ops from HF file without downloading weights (#21182)

* tests: allow exporting graph ops from HF file without downloading weights

* use unique_ptr for llama_context in HF metadata case

* fix missing non-required tensors falling back to type f32

* use unique pointers where possible

* use no_alloc instead of fixing f32 fallback

* fix missing space

tests/gguf-model-data.h

@@ -1,6 +1,7 @@
 #pragma once
 
-#include "ggml.h"
+#include "ggml-cpp.h"
+#include "gguf.h"
 
 #include <cstdint>
 #include <optional>
@@ -40,3 +41,8 @@ std::optional<gguf_remote_model> gguf_fetch_model_meta(
     const std::string & repo,
     const std::string & quant = "Q8_0",
     const std::string & cache_dir = "");  // empty = default
+
+gguf_context_ptr gguf_fetch_gguf_ctx(
+    const std::string & repo,
+    const std::string & quant = "Q8_0",
+    const std::string & cache_dir = "");