cmake : do not include ./src as public for libllama (#13062)

* cmake : do not include ./src as public for libllama

ggml-ci

* cmake : rework tests

ggml-ci

* llguidance : remove unicode include

ggml-ci

* cmake : make c++17 private

ggml-ci

tests/test-tokenizer-1-spm.cpp

@@ -1,8 +1,9 @@
 #include "llama.h"
 #include "common.h"
-#include "unicode.h"
 #include "console.h"
 
+#include "../src/unicode.h"
+
 #include <cassert>
 #include <codecvt>
 #include <cstdio>