Implement lookup retry mechanism #122
Description
Currently, when HTTP request fails, Optional.empty() is returned. Instead, we should retry the request configurable number of times. In addition, we should distinguish retryable errors from non-retryable ones (e.g. 400 Bad Request vs 503 Service Unavailable).
Flink already provides org.apache.flink.table.connector.source.lookup.LookupOptions#MAX_RETRIES.