### 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_
"""
    We override FakeMultipart to prevent `complete` to load every single part into memory.
    """
    def __init__(self, *args, **kwargs):
        super(StreamedFakeMultipart, self).__init__(*args, **kwargs)
        self.parts: dict[int, StreamedFakeKey] = {}
    def complete(self, body: Iterator[Tuple[int, str]]) -> Tuple[SpooledTemporaryFile, str]:
        decode_hex = codecs.getdecoder("hex_codec")
        
        total = SpooledTemporaryFile(max_size=S3_MAX_FILE_SIZE_BYTES)
        md5s = bytearray()
        last = None
        count = 0
        for pn, etag in body:
            part = self.parts.get(pn)
            part_etag = None
            if part is not None:
                part_etag = part.etag.replace('"', "")
                etag = etag.replace('"', "")
            if part is None or part_etag != etag:
                total.close()
                raise s3_exceptions.InvalidPart()
            if last is not None and last.contentsize < S3_UPLOAD_PART_MIN_SIZE:
                total.close()
                raise s3_exceptions.EntityTooSmall()
            md5s.extend(decode_hex(part_etag)[0])
            
            stream_value = part.value
            with part.lock: