Add Bazel build support

New addon -- KafkaMetrics

Make ConsumerRecord to be copyable

Fix KafkaRecoverableProducer.close()

Some slight fix for KafkaRecoverableProducer

Add purge() interface for KafkaProducer, and improve the KafkaProduce…

…r::close()

Fix macro COMPILER_SUPPORTS_CPP_17

Add error notification for some testcases

Add test description in README

Improve CMakeLists