Clustered: observability and query tracing

Teach customers (esp. Dedicated and Clustered) how to add trace-ids to Flight queries when using client libraries.

Document the debug option
Document (link to example of) the Flight middle-ware option FlightReader accepts middle-ware so we can define a simple middleware factory and have that inject a trace header (and dump the output header). See the Flight repo (https://github.com/apache/arrow/blob/ac7e9a4c41b73242b2f7a15f13f3c8fde843416d/python/examples/flight/middleware.py#L68)

Define the middleware:


class TracingClientMiddleWareFactory(flight.ClientMiddleware):
    def start_call(self, info):
        print("Starting new call:", info)
        return TracingClientMiddleware()

class TracingClientMiddleware(flight.ClientMiddleware):
    def sending_headers(self):
        print("Sending trace ID:", "BensTraceHeader")
        return {
            "x-tracing-id": "BensTraceHeader",
        }

    def received_headers(self, headers):
        if "trace-id" in headers:
            trace_id = headers["trace-id"][0]
            print("Found trace header with value:", trace_id)
            # Don't overwrite our trace ID```
Then, pass the factory into the V3 client via `flight_client_options`:
```    client = InfluxDBClient3(token = TOOLS_TOKEN,
                        host = TOOLS_URL,
                        org = TOOLS_ORG,
                        database="influxql_query_log",
                        flight_client_options={"middleware": (TracingClientMiddleWareFactory(),)}
                        )```
Run yer query and get lovely trace-id goodness
```ben@ratchett:~/Repos/c2_usage_extraction_scripts$ QUERY_INTERVAL='30 minutes' influxql/ticket_114205.py 58fa619b8b55b03e
SELECT request FROM influxql_query_log WHERE time &gt; now() - interval '30 minutes' AND "orgID" = '58fa619b8b55b03e' 
Fetching queries from Tools
Starting new call: CallInfo(method=&lt;FlightMethod.DO_GET: 5&gt;)
Sending trace ID: BensTraceHeader
Found trace header with value: b6c3a9e01d758a13```

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influxdata / docs-v2

Clustered: observability and query tracing #5143