DynamoDB. Additional On Update behavior for particular attribute.

### Describe the feature

Current SDK v2 has UpdateBehavior enum. It contains only WRITE_ALWAYS and WRITE_IF_NOT_EXISTS. It would be great to have additional enum to define the updated policy for elements in the collection attribute's type as like Set/List. Something like `list_appent()` in update expression but for DynamoDbBean

### Is your Feature Request related to a problem?

No.

### Proposed Solution

Additional enum APPEND_ON_COLLECTION inside of UpadteBehavior annotation applied only for Set/List attribute.
On UpdateItem action all elements of the collection's attribute should add to the existing ones. In the List case elements can contain duplicates and don't contain in the Set case.

### Describe alternatives you've considered

_No response_

### Acknowledge

- [x] I may be able to implement this feature request

### AWS Java SDK version used

2.17.97

### JDK version used

openjdk 11.0.13 2021-10-19 OpenJDK Runtime Environment Temurin-11.0.13+8 (build 11.0.13+8) OpenJDK 64-Bit Server VM Temurin-11.0.13+8 (build 11.0.13+8, mixed mode)

### Operating System and version

MacOS 12.0.1

Beginne damit, das UpdateBehavior-Enum oder die Annotation sowie die für UpdateItem-Operationen verwendete DynamoDbBean-Verarbeitung zu lokalisieren. Verfolge, wie Sammlungsattribute derzeit aktualisiert werden, und definiere und teste anschließend das angeforderte APPEND_ON_COLLECTION-Verhalten für Listen und Sets, einschließlich Duplikaten in Listen und der Eindeutigkeit von Sets.

Vom Indexierungsmodell aus dem Issue-Text verfasst.