As reported in https://github.com/localstack/localstack/issues/6659#issuecomment-1630932643_, `HeadObject` does not respect `ChecksumMode`. 


```shell
at 09:31:57 ➜ AWS_DEFAULT_REGION=us-west-1 aws --endpoint-url=http://localhost:4566 s3api create-bucket --bucket test-bucket --create-bucket-configuration LocationConstraint=us-west-1
{
    "Location": "http://test-bucket.s3.localhost.localstack.cloud:4566/"
}

at 09:32:13 ➜ aws --endpoint-url=http://localhost:4566 s3api put-object --bucket test-bucket --key file.json --body README.md --checksum-algorithm SHA256
{
    "ETag": "\"4bb2f1387449d690bff6336ea255909c\"",
    "ChecksumSHA256": "bzOikXXMUqRTCrpVq7Pt7LjJ0fjR3ccUfM19S/gnfqA="
}

# SHA256 missing here
at 09:32:20 ➜ aws --endpoint-url=http://localhost:4566 s3api head-object --bucket test-bucket --key file.json --checksum-mode Enabled
{
    "AcceptRanges": "bytes",
    "LastModified": "2023-07-11T13:32:15+00:00",
    "ContentLength": 1455,
    "ETag": "\"4bb2f1387449d690bff6336ea255909c\"",
    "ContentType": "binary/octet-stream",
    "Metadata": {}
}
```

Note the equivalent response from S3 actual includes the SHA256 value

```shell
at 10:21:23 ➜ aws s3api head-object --bucket test-bucket --key file.json --checksum-mode Enabled
{
    "AcceptRanges": "bytes",
    "Expiration": "expiry-date=\"Thu, 13 Jul 2023 00:00:00 GMT\", rule-id=\"all\"",
    "LastModified": "2023-07-11T14:21:09+00:00",
    "ContentLength": 1956,
    "ChecksumSHA256": "bj7fqCqtaF95M1ULwQRDJuHbL/Xd9NVMH6pua9OINcc=",
    "ETag": "\"f4be535d45019a4408dd5369986919f8\"",
    "ContentEncoding": "",
    "ContentType": "binary/octet-stream",
   
    "Metadata": {},
    
}
```

_Originally posted by @bdurrani in https://github.com/localstack/localstack/issues/6659#issuecomment-1630932643_
            
if not context:
            return s3_stores[get_aws_account_id()][aws_stack.get_region()]
        return s3_stores[context.account_id][context.region]
    def _clear_bucket_from_store(self, bucket: BucketName):
        store = self.get_store()
        store.bucket_lifecycle_configuration.pop(bucket, None)
        store.bucket_versioning_status.pop(bucket, None)
        store.bucket_cors.pop(bucket, None)
        store.bucket_notification_configs.pop(bucket, None)
        store.bucket_replication.pop(bucket, None)
        store.bucket_website_configuration.pop(bucket, None)
        store.bucket_analytics_configuration.pop(bucket, None)
        store.bucket_intelligent_tiering_configuration.pop(bucket, None)
        self._expiration_cache.pop(bucket, None)
    def on_after_init(self):
        apply_moto_patches()
        preprocess_request.append(self._cors_handler)
        register_website_hosting_routes(router=ROUTER)
        register_custom_handlers()
        
        
    def __init__(self) -> None:
        super().__init__()
        self._notification_dispatcher = NotificationDispatcher()
        self._cors_handler = S3CorsHandler()
        
        
        self._expiration_cache: dict[BucketName, dict[ObjectKey, Expiration]] = defaultdict(dict)
    def on_before_stop(self):