Support importing/updating of S3 bucket policy

### Name of the resource

AWS::S3::BucketPolicy

### Resource name

_No response_

### Description

Currently, when trying to update the bucket policy via CloudFormation it will causing the error 'The bucket policy already exists on bucket'. In order to make changes, customer needs to delete and reapply policy, which will cause an outage because of this action.

In short, In order to update bucket policy we would need to delete and recreate it.

### Other Details

_No response_

The request concerns AWS::S3::BucketPolicy and the CloudFormation update path, but it names no repository files, tests, or entry points. Start by locating how bucket policies are imported and updated; done means policy changes apply without requiring deletion and recreation, avoiding an outage.

Written by the indexing model from the issue text.