[feat]: Add search_mode support to OpenAI vector store API

Add search_mode parameter (vector/keyword/hybrid) to openai_search_vector_store
method. Fixes OpenAPI
code generation by using str instead of Literal type.

Signed-off-by: Varsha Prasad Narsing <varshaprasad96@gmail.com>

docs/_static/llama-stack-spec.html

@@ -13943,6 +13943,10 @@
                     "rewrite_query": {
                         "type": "boolean",
                         "description": "Whether to rewrite the natural language query for vector search (default false)"
+                    },
+                    "search_mode": {
+                        "type": "string",
+                        "description": "The search mode to use - \"keyword\", \"vector\", or \"hybrid\" (default \"vector\")"
                     }
                 },
                 "additionalProperties": false,

docs/_static/llama-stack-spec.yaml

@@ -9737,6 +9737,10 @@ components:
           description: >-
             Whether to rewrite the natural language query for vector search (default
             false)
+        search_mode:
+          type: string
+          description: >-
+            The search mode to use - "keyword", "vector", or "hybrid" (default "vector")
       additionalProperties: false
       required:
         - query