Concurrent consumers support

[kjamrog]

Changes:

• instead of operating on consumer field in AbstractSqsConsumer, we use consumers array now
• number of consumers can be specified with concurrentConsumersAmount option
• added messageProcessingTime and messageType to the log for better observability

[kibertoad]

I would do the check on the log level for this.logger first and skip it entirely if it's below debug

[kjamrog]

From what I see Logger is a generic interface and it does not expose any property for log level. We could check level property as it's available in pino, but it won't apply all of the time

[kibertoad]

we should switch to CommonLogger interface from the node-core, it exposes the isLevelEnabled method from pino

[kjamrog]

So we should probably change it everywhere and since logger is provided from outside that will be breaking change. Should I address it in separate PR then?

[kibertoad]

yeah, makes sense

[kjamrog]

Here is the draft PR with logger update: #233

I will add level condition there after this PR is merged