Make agent warn about possibly misconfigured gauge/counter

[bsmid]

One common source of issues in newly created integrations is a mix-up between counter and gauge types. Since agent is processing live data, it could also warn of the cases where:

• metric was defined as a gauge, but in reality it should be a counter - Agent can notice cases like this one if particular metric is behaving like a cumulative (it is always either staying the same or increasing)
• metric was defined as a counter, but in reality it is more likely it is a gauge - in this case behavior is opposite from the one described in previous point - metric goes in all directions (up, down, stays the same)

In both cases observation has to be done at the source (not in agent's output) and over prolonged period of time (it is not enough to take just few consecutive measurements).

This tracking logic should most likely be enabled only in DEBUG mode (or some newly introduced testing mode) as it will have its own overhead.

Agent should print what it finds into the log.