Upgrade 1.5.2 and improve debugging

[TsuyoshiUshio]

This PR includes

• Upgrade Confluent.Kafka 1.5.2
• Adding Following Libkafka properties with default values.
• Add Log to identify if users use SingleFunctionExecutor or MultipleFunctionExecutor
• Redirect Libkafka Log to the ILogger

Setting	librdkafka property	default	Trigger or Output
LibkafkaDebug	debug	null	Both
MetadataMaxAgeMs	metadata.max.age.ms	180000	Both
SocketKeepaliveEnable	socket.keepalive.enable	true	Both

Upgrade Confluent Kafka for avoiding limitation for Azure about the log-lived TCP Connection

The reason of the default settings, refer to this issue

Add Log to detect which FunctionExecutor do they use?

For the log of FunctionExecutor, I'd like to know if a user uses Single or Multiple Function Executor for diagnosing an issue.
If there is a better place, please let me know.

Redirect the Log of Libkafka native library

Currently, the Libkafka message is showed up standard output, that means there is no way to fetch it from Application Insights or other logging system.

Debug option enables librdkafka logging. https://github.com/edenhill/librdkafka

Fix

#185
#187

[TsuyoshiUshio]

I upgrade the Confluent.Kafka library to 1.5.2
Also, I add topic.metadata.refresh.interval.ms configuration support for EventHubs.
confluentinc/librdkafka#3109

[TsuyoshiUshio]

I update this PR according to the #187