runner.go: Better abstract vision model integration

-Update mllama to take the cross attention state as embeddings in
a batch, more similar to how Llava handles it. This improves
integration with the input cache.
-Pass locations in a prompt for embeddings using tags similar to Llava.
-Abstract interface to vision models so the main runner accesses Clip
and Mllama similarly

Co-authored-by: Michael Yang <mxyng@pm.me>

llama/llama.h

@@ -266,6 +266,7 @@ extern "C" {
 
         llama_token  *  token;
         float        *  embd;
+        int32_t         n_embd;
         llama_pos    *  pos;
         int32_t      *  n_seq_id;
         llama_seq_id ** seq_id;
@@ -451,7 +452,7 @@ extern "C" {
 
     // TODO (jmorganca): this should most likely be passed in as part of a batch
     // and not set on the context for all batches.
-    LLAMA_API void llama_set_cross_attn_state(struct llama_context * ctx, float * cross_attn_state);
+    LLAMA_API void llama_set_cross_attention(struct llama_context * ctx, bool cross_attn_state);
 
     // Frees all allocated memory
     LLAMA_API void llama_free(struct llama_context * ctx);