### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

- Localstack fails with HTTP 500, error code "InternalError", message "not enough values to unpack (expected 2, got 1)" when `CopySource` is an invalid string for `copy_object` API.

### Expected Behavior

- For the same API `copy_object`, the cloud fails with HTTP 400, error code "InvalidArgument".
- Localstack should handle invalid `CopySource` i.e., it is a dictionary with one value or an invalid string not adhering to "{bucket}/{key}" format.

### How are you starting LocalStack?

With a `docker run` command

### 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)

    botoclient.copy_object(CopySource="Invalid_random_string", Bucket="test_bucket", Key=key) 


 test_bucket is a valid bucket.  

### Environment

```markdown
- OS: Ubuntu 22.04.2 LTS
- LocalStack: 2.1.0
- boto3: 1.28.6
```


### Anything else?

_No response_
aws_client.s3.put_bucket_versioning(
            Bucket=bucket_name,
            VersioningConfiguration={"Status": "Suspended"},
        )
        rs = aws_client.s3.get_bucket_versioning(Bucket=bucket_name)
        snapshot.match("get_bucket_versioning_suspended", rs)
    @markers.aws.validated
    @markers.snapshot.skip_snapshot_verify(
        paths=["$..Delimiter", "$..EncodingType", "$..VersionIdMarker"]
    )
    @markers.snapshot.skip_snapshot_verify(
        condition=is_v2_provider,
        paths=["$..ServerSideEncryption"],
    )
    def test_s3_put__versioned(self, s3_bucket, snapshot, aws_client):
        snapshot.add_transformer(snapshot.transform.s3_api())
        # this 
        key = "non-version-bucket-key"
        put_obj_pre_versioned = aws_client.s3.put_(
            Bucket=s3_bucket, Key=key, Body="non-versioned-key"
        )
        snapshot.match("put-pre-versioned", put_obj_pre_versioned)
        get_obj_pre_versioned = aws_client.s3.get_(Bucket=s3_bucket, Key=key)
        snapshot.match("get-pre-versioned", get_obj_pre_versioned)
        list_obj_pre_versioned = aws_client.s3.list__versions(Bucket=s3_bucket)
        snapshot.match("list--pre-versioned", list_obj_pre_versioned)
        # we a
        aws_client.s3.put_bucket_versioning(
            Bucket=s3_bucket,
            VersioningConfiguration={"Status": "Enabled"},