Remove direct access to std streams from "run"

The goal is to allow running "run" while connected to other streams,
such as TCP sockets.

Signed-off-by: Thiago Padilha <thiago@padilha.cc>

run.h

@@ -3,4 +3,8 @@
 #include "llama.h"
 #include "utils.h"
 
-int run(llama_context * ctx, gpt_params params);
+int run(llama_context * ctx,
+        gpt_params params,
+        std::istream & instream,
+        FILE *outstream,
+        FILE *errstream);