Support AWS bedrock for reranker

### 🚀 The feature

Support config like: 
```
"reranker": {
        "provider": "aws_bedrock",
        "config": {
            "model": "cohere.rerank-v3-5:0",
            "top_n": 5
        }
    },
```

### Motivation, pitch

I am on AWS ecosystem and want to use reranker model there