### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

CopyObject API does not check precondition headers such as `x-amz-copy-source-if-modified-since`. Instead it seems to always copy the object.

### Expected Behavior

The API should return a 412 response with content similar to:

```
<Error><Code>PreconditionFailed</Code><Message>At least one of the pre-conditions you specified did not hold</Message><Condition>x-amz-copy-source-If-Modified-Since</Condition><RequestId>14HR9PXJRG5B1GR5</RequestId><HostId>HztBs2jYea1fzzPWo1JWy33NQJqo1S1IsK62rkbnVEI04PnGNCi8sPVrichGQxH3FQwLA2RIyF4=</HostId></Error>
```

### How are you starting LocalStack?

With a docker-compose file

### Steps To Reproduce

#### How are you starting localstack (e.g., `bin/localstack` command, arguments, or `docker-compose.yml`)

    docker run localstack/localstack

#### Client commands (e.g., AWS SDK code snippet, or sequence of "awslocal" commands)

```
aws s3  --profile localstack --endpoint-url http://s3.localhost.localstack.cloud:4566 \
  ls s3://net-amazon-s3-test/Makefile.am
2023-01-25 10:47:40        537 Makefile.am

aws s3api copy-object --copy-source net-amazon-s3-test/Makefile.am --key Makefile.am.2 \
  --bucket net-amazon-s3-test2 --profile localstack --endpoint-url http://s3.localhost.localstack.cloud:4566 \
  --copy-source-if-modified-since "Wed, 25 Jan 2023 16:16:27 GMT"
{
    "CopyObjectResult": {
        "ETag": "\"46ada9d1fe8f8a311ff4504c226e061c\"",
        "LastModified": "2023-01-25T16:18:43+00:00"
    }
}
```

### Environment

```markdown
- OS: penguin
- LocalStack: latest
```


### Anything else?

_No response_
request_without_body["Body"] = BytesIO(b"")
            response: PutObjectOutput = call_moto_with_request(
                context,
                request_without_body,
            )
        except CommonServiceException as e:
            
            if e.code == "InvalidStorageClass":
                raise InvalidStorageClass(
                    "The storage class you specified is not valid",
                    StorageClassRequested=request.get("StorageClass"),
                )
            raise
        
        
        
        key_object = get_key_from_moto_bucket(moto_bucket, key=request["Key"])
        key_object: StreamedFakeKey
        checksum_algorithm = request.get("ChecksumAlgorithm")
        
        checksum_value = (
            request.get(f"Checksum{checksum_algorithm.upper()}") if checksum_algorithm else None
        )
        key_object.checksum_value = checksum_value or None
        key_object.checksum_algorithm = checksum_algorithm
        headers = context.request.headers
        content_sha_256 = context.request.headers.get("x-amz-content-sha256") or ""
        try:
            if content_sha_256.startswith("STREAMING-"):