app : introduce the llama unified executable (#23296)

* app : introduce the llama unified executable

Signed-off-by: Adrien Gallouët <angt@huggingface.co>

* Use serve for server

Signed-off-by: Adrien Gallouët <angt@huggingface.co>

* Hide completion and bench, add help command

Signed-off-by: Adrien Gallouët <angt@huggingface.co>

* Remove STATIC

Signed-off-by: Adrien Gallouët <angt@huggingface.co>

* Use -impl targets instead of -lib

Signed-off-by: Adrien Gallouët <angt@huggingface.co>

* Revert "Remove STATIC"

This reverts commit cc44caccb9902b34a3531633edac911e5b3d65cd.

---------

Signed-off-by: Adrien Gallouët <angt@huggingface.co>

tools/completion/main.cpp

@@ -0,0 +1,5 @@
+int llama_completion(int argc, char ** argv);
+
+int main(int argc, char ** argv) {
+    return llama_completion(argc, argv);
+}