Filebeat module for APM Server

[graphaelli]

As part of [monitoring the Elastic stack with Filebeat], we'll want a new Filebeat module for APM server.

[elasticmachine]

Pinging @elastic/stack-monitoring (Stack monitoring)

[cachedout]

Hi @graphaelli. The bot pinged the Stack Monitoring team but you may want @elastic/beats-contributors to see this as well. :)

[botelastic]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[willemdh]

@graphaelli This shouldn't be closed no?

[axw]

In the future APM Server will integrate with Elastic Agent, which will know how to collect logs and metrics for APM Server; this will remove the need for an APM Server-specific Filebeat module.