Convert DynamoDBAttributeValue to AttributeValue type from SDK V2

I am writing a lambda function to respond to changes in a DynamoDB table and process new items. Currently the lambda handler takes a DynamoDBEvent object defined in this repo as a parameter. Within this object, the database object is represented as a `map[string]DynamoDBAttributeValue`. It seems that this `DynamoDBAttributeValue` behaves quite differently to the `AttributeValue` type defined in the SDK (https://pkg.go.dev/github.com/aws/aws-sdk-go-v2/service/dynamodb/types#AttributeValue), and for example I cannot use the same `attributevalue.UnmarshalMap` method to unmarshal the map to a concrete Go type.

**Describe the solution you'd like**
The ideal solution would be to have one and only one definition of `AttributeValue` shared between both repos. Since this is likely not possible for backwards compatibility, another solution would be to add a helper method to convert between the two distinct type representations of the same logical object.

**Describe alternatives you've considered**
I've tried using the `DynamoDBAttributeValue` type as-is, but the lack of helper methods to convert to my existing Go types is frustrating and makes the code much more susceptible to runtime panics when asserting the shape of the response object.

Thanks for any help or advice if I have missed something that already exists here.