Add support for Logstasher

[kford-newrelic]

Is your feature request related to a problem? Please describe.

From the support issue:

• "Logstasher functions in a way that is not compatible with the way the agent instruments the Ruby Logger class."
• "Currently the log decorator isn't compatible with json logs, so that would also need to be implemented."

Feature Description

Add ability to automatically instrument and forward Logstasher logs. Additionally, add local log decoration.

Describe Alternatives

N/A

Additional context

Original FR - NR-169467

Priority

Really Want

[workato-integration]

https://new-relic.atlassian.net/browse/NR-216496

[kaylareopelle]

Relates to #2341, since they both have the JSON-style logs. The agent spec on JSON log formatted logs must be merged before we can work on this.

[fallwith]

As @kaylareopelle mentions above in reference to #2341, there are 2 key aspects to this issue:

• Supporting JSON formatted log data
• Supporting the Logstasher gem's functions

When we work on this one, let's be sure that the JSON handling side of things is implemented generically for re-use by Semantic Logger and other JSON based logger libraries, whether that means code reuse with modules or some other DRY approach.