Add KafkaMetricsRegistry

[Z1kkurat]

This issue addresses evolution-gaming/smetrics#237 with the implementation initially developed in evolution-gaming/smetrics#243.

[coveralls]

Pull Request Test Coverage Report for Build 4363844742

• 0 of 22 (0.0%) changed or added relevant lines in 4 files are covered.
• 33 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-1.02%) to 75.542%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
skafka/src/main/scala/com/evolutiongaming/skafka/metrics/syntax.scala	0	2	0.0%
skafka/src/main/scala/com/evolutiongaming/skafka/metrics/MeteredConsumerOf.scala	0	3	0.0%
skafka/src/main/scala/com/evolutiongaming/skafka/metrics/MeteredProducerOf.scala	0	3	0.0%
skafka/src/main/scala/com/evolutiongaming/skafka/metrics/KafkaMetricsRegistry.scala	0	14	0.0%

Files with Coverage Reduction	New Missed Lines	%
skafka/src/main/scala/com/evolutiongaming/skafka/consumer/ConsumerMetrics.scala	1	95.65%
skafka/src/main/scala/com/evolutiongaming/skafka/producer/ProducerLogging.scala	4	38.46%
skafka/src/main/scala/com/evolutiongaming/skafka/consumer/ConsumerLogging.scala	28	69.66%

Totals
Change from base Build 4303900645:	-1.02%
Covered Lines:	1325
Relevant Lines:	1754

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💛 - Coveralls

[dfakhritdinov]

@Z1kkurat, thanks for the proposal!

What do you think about adding artificial metric label to overcome case with empty clientId to avoid metrics from different consumer/producer instances to clash? In the registry you already introduced UUID for each metric source, might be it can be used also to explicitly differentiate those sources?

Update: not really sure about re-using UUID as it brings high cardinality into Prometheus labels, AFAIK its not so good idea