Add support for collection exception details in log lines from in-agent log forwarding

[jaffinito]

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Describe the story, please be clear on scope of the story.

This work will add the capturing of exception details to our existing in-agent log forwardng. Specifically:

• error.message: Exception.Message
• error.stack: Exception.StackTrace
• error.class: Exception class name

If an exception is present in the log event, the 3 attributes above will be added to log event json at the same level as message, level, and timestamp, i.e. on the individual message, not in the common section.

Acceptance Criteria

• Captures exception from log messages from all support frameworks
• agent API has been updated to accept these
• Unit tests (AgentWrapperApiTests) updated
• Updates integration tests to support testing these. Recommend using the existing "Error" level and replacing the string with Exception.

Describe Design Consideration/Limitations

None.

Additional context

Spec: https://source.datanerd.us/agents/agent-specs/pull/579