Deleting a non-existent key through s3api's delete-objects should return a valid response..

```
aws s3api delete-objects --bucket my-bucket --delete '{\"Objects\":[{\"Key\":\"my-key\"}]}'
```
Gives...
```
{
    "Deleted": [
        {
            "Key": "my-key"
        }
    ]
}
```

Deleting a non-existent key through s3api's delete-objects on LocalStack returns an error response without any additional information beyond the key.

```
aws s3api delete-objects --bucket my-bucket --delete '{"Objects":[{"Key":"my-key"}]}' --endpoint-url http://localhost:4572
```
Gives...
```
{
    "ResponseMetadata": {
        "HTTPStatusCode": 200,
        "HTTPHeaders": {
            "server": "BaseHTTP/0.6 Python/3.7.5",
            "date": "Fri, 20 Dec 2019 16:02:39 GMT",
            "content-type": "application/xml; charset=utf-8",
            "content-length": "180",
            "access-control-allow-origin": "*",
            "last-modified": "Fri, 20 Dec 2019 16:02:39 GMT",
            "access-control-allow-methods": "HEAD,GET,PUT,POST,DELETE,OPTIONS,PATCH",
            "access-control-allow-headers": "authorization,content-type,content-md5,cache-control,x-amz-content-sha256,x-amz-date,x-amz-security-token,x-amz-user-agent,x-amz-target,x-amz-acl,x-amz-version-id,x-localstack-target,x-amz-tagging",
            "access-control-expose-headers": "x-amz-version-id"
        },
        "RetryAttempts": 0
    },
    "Errors": [
        {
            "Key": "my-key"
        }
    ]
}
```

Deleting an existent key seems to work fine.
""" check whether any of the event types in `events` matches the
        given `action` and `api_method`, and return the first match. """
    events = events or []
    for event in events:
        regex = event.replace('*', '[^:]*')
        action_string = 's3:%s:%s' % (action, api_method)
        match = re.match(regex, action_string)
        if match:
            return match
    return False
def filter_rules_match(filters, object_path):
    """ check whether the given object path matches all of the given filters """
    filters = filters or {}
    s3_filter = _get_s3_filter(filters)
    for rule in s3_filter.get('FilterRule', []):
        rule_name_lower = rule['Name'].lower()
        if rule_name_lower == 'prefix':
            if not prefix_with_slash(object_path).startswith(prefix_with_slash(rule['Value'])):
                return False
        elif rule_name_lower == 'suffix':
            if not object_path.endswith(rule['Value']):
                return False
        else:
            LOGGER.warning('Unknown filter name: "%s"' % rule['Name'])
    return True
def _get_s3_filter(filters):