feat: add batch inference API to llama stack inference

tests/integration/test_cases/inference/chat_completion.json

@@ -537,5 +537,31 @@
         }
       ]
     }
+  },
+  "batch_completion": {
+    "data": {
+      "qa_pairs": [
+        {
+          "question": "What is the capital of France?",
+          "answer": "Paris"
+        },
+        {
+          "question": "Who wrote the book '1984'?",
+          "answer": "George Orwell"
+        },
+        {
+          "question": "Which planet has rings around it with a name starting with letter S?",
+          "answer": "Saturn"
+        },
+        {
+          "question": "When did the first moon landing happen?",
+          "answer": "1969"
+        },
+        {
+          "question": "What word says 'hello' in Spanish?",
+          "answer": "Hola"
+        }
+      ]
+    }
   }
 }

tests/integration/test_cases/inference/completion.json

@@ -44,5 +44,18 @@
                 "year_retired": "2003"
             }
         }
+    },
+    "batch_completion": {
+        "data": {
+            "contents": [
+                "Micheael Jordan is born in ",
+                "Roses are red, violets are ",
+                "If you had a million dollars, what would you do with it? ",
+                "All you need is ",
+                "The capital of France is ",
+                "It is a good day to ",
+                "The answer to the universe is "
+            ]
+        }
     }
 }