implement embedding generation in supported inference providers (#589)

This PR adds the ability to generate embeddings in all supported
inference providers.

```
pytest -v -s llama_stack/providers/tests/inference/test_embeddings.py -k "bedrock" --inference-model="amazon.titan-embed-text-v2:0"  --env EMBEDDING_DIMENSION=1024

 pytest -v -s -k "vllm"  --inferrence-model="intfloat/e5-mistral-7b-instruct"  llama_stack/providers/tests/inference/test_embeddings.py --env EMBEDDING_DIMENSION=4096  --env VLLM_URL="http://localhost:9798/v1"

pytest -v -s --inference-model="nomic-ai/nomic-embed-text-v1.5"  llama_stack/providers/tests/inference/test_embeddings.py  -k "fireworks"  --env FIREWORKS_API_KEY=<API_KEY>--env EMBEDDING_DIMENSION=128

pytest -v -s --inference-model="togethercomputer/m2-bert-80M-2k-retrieval"  llama_stack/providers/tests/inference/test_embeddings.py  -k "together"  --env TOGETHER_API_KEY=<API_KEY>--env EMBEDDING_DIMENSION=768

pytest -v -s -k "ollama"  --inference-model="all-minilm:v8"  llama_stack/providers/tests/inference/test_embeddings.py --env EMBEDDING_DIMENSION=384

 torchrun $CONDA_PREFIX/bin/pytest -v -s -k "meta_reference" --inference-model="sentence-transformers/all-MiniLM-L6-v2"  llama_stack/providers/tests/inference/test_embeddings.py --env EMBEDDING_DIMENSION=384

```

llama_stack/providers/inline/memory/faiss/faiss.py

@@ -19,11 +19,10 @@ from numpy.typing import NDArray
 from llama_models.llama3.api.datatypes import *  # noqa: F403
 
 from llama_stack.apis.memory import *  # noqa: F403
-from llama_stack.providers.datatypes import MemoryBanksProtocolPrivate
+from llama_stack.providers.datatypes import Api, MemoryBanksProtocolPrivate
 from llama_stack.providers.utils.kvstore import kvstore_impl
 
 from llama_stack.providers.utils.memory.vector_store import (
-    ALL_MINILM_L6_V2_DIMENSION,
     BankWithIndex,
     EmbeddingIndex,
 )
@@ -32,7 +31,8 @@ from .config import FaissImplConfig
 
 logger = logging.getLogger(__name__)
 
-MEMORY_BANKS_PREFIX = "memory_banks:v1::"
+MEMORY_BANKS_PREFIX = "memory_banks:v2::"
+FAISS_INDEX_PREFIX = "faiss_index:v2::"
 
 
 class FaissIndex(EmbeddingIndex):
@@ -56,7 +56,7 @@ class FaissIndex(EmbeddingIndex):
         if not self.kvstore:
             return
 
-        index_key = f"faiss_index:v1::{self.bank_id}"
+        index_key = f"{FAISS_INDEX_PREFIX}{self.bank_id}"
         stored_data = await self.kvstore.get(index_key)
 
         if stored_data:
@@ -85,16 +85,25 @@ class FaissIndex(EmbeddingIndex):
             "faiss_index": base64.b64encode(buffer.getvalue()).decode("utf-8"),
         }
 
-        index_key = f"faiss_index:v1::{self.bank_id}"
+        index_key = f"{FAISS_INDEX_PREFIX}{self.bank_id}"
         await self.kvstore.set(key=index_key, value=json.dumps(data))
 
     async def delete(self):
         if not self.kvstore or not self.bank_id:
             return
 
-        await self.kvstore.delete(f"faiss_index:v1::{self.bank_id}")
+        await self.kvstore.delete(f"{FAISS_INDEX_PREFIX}{self.bank_id}")
 
     async def add_chunks(self, chunks: List[Chunk], embeddings: NDArray):
+        # Add dimension check
+        embedding_dim = (
+            embeddings.shape[1] if len(embeddings.shape) > 1 else embeddings.shape[0]
+        )
+        if embedding_dim != self.index.d:
+            raise ValueError(
+                f"Embedding dimension mismatch. Expected {self.index.d}, got {embedding_dim}"
+            )
+
         indexlen = len(self.id_by_index)
         for i, chunk in enumerate(chunks):
             self.chunk_by_index[indexlen + i] = chunk
@@ -124,8 +133,9 @@ class FaissIndex(EmbeddingIndex):
 
 
 class FaissMemoryImpl(Memory, MemoryBanksProtocolPrivate):
-    def __init__(self, config: FaissImplConfig) -> None:
+    def __init__(self, config: FaissImplConfig, inference_api: Api.inference) -> None:
         self.config = config
+        self.inference_api = inference_api
         self.cache = {}
         self.kvstore = None
 
@@ -139,10 +149,11 @@ class FaissMemoryImpl(Memory, MemoryBanksProtocolPrivate):
         for bank_data in stored_banks:
             bank = VectorMemoryBank.model_validate_json(bank_data)
             index = BankWithIndex(
-                bank=bank,
-                index=await FaissIndex.create(
-                    ALL_MINILM_L6_V2_DIMENSION, self.kvstore, bank.identifier
+                bank,
+                await FaissIndex.create(
+                    bank.embedding_dimension, self.kvstore, bank.identifier
                 ),
+                self.inference_api,
             )
             self.cache[bank.identifier] = index
 
@@ -166,13 +177,13 @@ class FaissMemoryImpl(Memory, MemoryBanksProtocolPrivate):
         )
 
         # Store in cache
-        index = BankWithIndex(
-            bank=memory_bank,
-            index=await FaissIndex.create(
-                ALL_MINILM_L6_V2_DIMENSION, self.kvstore, memory_bank.identifier
+        self.cache[memory_bank.identifier] = BankWithIndex(
+            memory_bank,
+            await FaissIndex.create(
+                memory_bank.embedding_dimension, self.kvstore, memory_bank.identifier
             ),
+            self.inference_api,
         )
-        self.cache[memory_bank.identifier] = index
 
     async def list_memory_banks(self) -> List[MemoryBank]:
         return [i.bank for i in self.cache.values()]