Add mysql2 instrumentation

[kaylareopelle]

Add instrumentation for the mysql2 gem, a "A simple, fast Mysql library for Ruby, binding to libmysql."

Spike Questions

Fill in the blanks/remove unrelated items before getting started...

• We plan to instrument the following methods:
• We plan to add the following metrics:
• We plan to add the following supportability metrics:
• We plan to add the following events:
• We will load this instrumentation based on the following conditions:

Consider the following questions and add responses if appropriate

• Are there other things, like samplers, that would be good to add?
• Where could conflicts with our existing instrumentation and structure come up?

Checklist

All items should be checked off before the issue is closed

Code

• [ ] Are there instrumentation options for chain and prepend?
• [ ] Has a new multiverse suite been created for the instrumentation?
  • [ ] If the gem is installed, does it load?
  • [ ] If the gem isn’t installed, does it skip?
  • [ ] Are errors raised by the gem we’ve instrumented being recorded by the agent?
  • [ ] Do any errors raised by New Relic code escape the agent?
  • [ ] Are the metrics we’ve added reporting?
  • [ ] Are the events we’ve added reporting?
• [ ] Can a new performance test be added for this instrumentation? (Probably no, but think about it for a sec…)
• [ ] How is the signal to noise ratio for the new data flowing from the agent? Is this new data valuable to customers? Does it overflow them with too much information?
• [ ] How are the methods we’ve instrumented helping our customers solve new problems?

Public documentation

• [ ] Has the Ruby agent requirements and supported frameworks document been updated to include support for this instrumentation?
• [ ] Have any new configuration options been added to:
  • [ ] Default Source
  • [ ] newrelic.yml
  • [ ] Config docs
• [ ] Have you added an entry to the Changelog?

Pull Request

• [ ] Have you attached a screenshot where the data is reporting in the UI?
• [ ] Do you have a blurb in the PR about why the instrumented method(s) were chosen?
• [ ] Does this instrumentation create any new metrics? What are they?
• [ ] Does this instrumentation create any new events? What are they?

[workato-integration[bot]]

https://issues.newrelic.com/browse/NEWRELIC-3342