Feature: Concatenate Partial/Split Container Logs

[dtbayles]

Summary

• Add parse-multiline-json.conf which allows users to concatenate split container logs without having to publish their own image (see tutorial here)
• This PR does not change or remove any existing behavior

Testing

• integration tests passing

make debug succeeded: yes
Integ tests succeeded: yes
New tests cover the changes: yes

Description for the changelog

Add .conf for concatenating split container logs

Licensing

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[dtbayles]

Context: this reduces the need for consumers of this service to publish their own image to ECR with just a few added lines in a .conf file and allows them to choose the new .conf file in their CDK infra. Ultimately saves time having to build one-off ECR publishing steps into existing CI/CD. Very lightweight change.