feat(api): Add options for supporting various embedding models (#1192)

We need to support:
- asymmetric embedding models (#934)
- truncation policies (#933)
- varying dimensional output (#932) 

## Test Plan

```bash
$ cd llama_stack/providers/tests/inference
$ pytest -s -v -k fireworks test_embeddings.py \
   --inference-model nomic-ai/nomic-embed-text-v1.5 --env EMBEDDING_DIMENSION=784
$  pytest -s -v -k together test_embeddings.py \
   --inference-model togethercomputer/m2-bert-80M-8k-retrieval --env EMBEDDING_DIMENSION=784
$ pytest -s -v -k ollama test_embeddings.py \
   --inference-model all-minilm:latest --env EMBEDDING_DIMENSION=784
```

llama_stack/providers/remote/inference/passthrough/passthrough.py

@@ -11,11 +11,13 @@ from llama_stack_client import LlamaStackClient
 from llama_stack.apis.common.content_types import InterleavedContent
 from llama_stack.apis.inference import (
     EmbeddingsResponse,
+    EmbeddingTaskType,
     Inference,
     LogProbConfig,
     Message,
     ResponseFormat,
     SamplingParams,
+    TextTruncation,
     ToolChoice,
     ToolConfig,
     ToolDefinition,
@@ -138,6 +140,9 @@ class PassthroughInferenceAdapter(Inference):
         self,
         model_id: str,
         contents: List[InterleavedContent],
+        text_truncation: Optional[TextTruncation] = TextTruncation.none,
+        output_dimension: Optional[int] = None,
+        task_type: Optional[EmbeddingTaskType] = None,
     ) -> EmbeddingsResponse:
         client = self._get_client()
         model = await self.model_store.get_model(model_id)
@@ -145,4 +150,7 @@ class PassthroughInferenceAdapter(Inference):
         return client.inference.embeddings(
             model_id=model.provider_resource_id,
             contents=contents,
+            text_truncation=text_truncation,
+            output_dimension=output_dimension,
+            task_type=task_type,
         )