Add WAF log convertor before sending to OpenSearch

Is your feature request related to a problem? Please describe.
It would be nice to have a convertor for WAF logs before sending to OpenSearch. If we want to build some Dashboard.

Describe the solution you'd like

• We want Data-prepper parse the web ACL name before sending to OpenSearch
• We need to distinguish between host and userAgent from ["httpRequest"]["headers"]

Additional context
Here are some parser code in Solution Centralized Logging with OpenSearch

class WAF(LogType):
    """An implementation of LogType for WAF Logs"""

    _format = "json"

    def parse(self, line: str):
        try:
            json_record = json.loads(line)

            # Extract web acl name, host and user agent
            json_record["webaclName"] = re.search(
                "[^/]/webacl/([^/]*)", json_record["webaclId"]
            ).group(1)
            headers = json_record["httpRequest"]["headers"]
            for header in headers:
                if header["name"].lower() == "host":
                    json_record["host"] = header["value"]
                elif header["name"].lower() == "user-agent":
                    json_record["userAgent"] = header["value"]
                else:
                    continue
            return json_record
        except Exception as e:
            logger.error(e)
            return {}

No file or test is named; start by locating Data Prepper's WAF log conversion path and the code that sends records to OpenSearch. Use the supplied parser as the behavioral reference: done means extracting the web ACL name and distinguishing host from userAgent in httpRequest headers before forwarding the record.