Move duplicated imatrix code into single common imatrix-loader.cpp (#22445)

* Deduplicate imatrix loading code

* Add back LLAMA_TRACE, early exit on quantize missing metadata

common/CMakeLists.txt

@@ -78,6 +78,8 @@ add_library(${TARGET}
     hf-cache.cpp
     hf-cache.h
     http.h
+    imatrix-loader.cpp
+    imatrix-loader.h
     json-partial.cpp
     json-partial.h
     json-schema-to-grammar.cpp