Support AttributeValue as property type on DDB Enhanced client

### Describe the feature

The DynamoDB Enhanced client should support `AttributeValue` as a property type.

### Use Case

Currently, I have a property that requires custom serialization/deserialization (mostly because the Enhanced Client refuses to support `Map` even with a custom converter), so I'm trying to declare a property of type `AttributeConverter`; however, this results in an exception:

```
java.lang.IllegalStateException: Converter not found for EnhancedType(software.amazon.awssdk.services.dynamodb.model.AttributeValue)
```

### Proposed Solution

A trivial no-op converter could be added to `DefaultAttributeConverterProvider`.

### Other Information

_No response_

### Acknowledgements

- [X] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

### AWS Java SDK version used

2.20.61

### JDK version used

OpenJDK 64-Bit Server VM Temurin-11.0.18+10 (build 11.0.18+10, mixed mode)

### Operating System and version

Gentoo Linux