Cherry-pick #18883 to 7.x: Add support for multiple sets of hints on autodiscover

[jsoriano]

Cherry-pick of PR #18883 to 7.x branch. Original message:

Enhancement

What does this PR do?

This PR allows defining multiple sets of annotations similar to how processors are defined. This functionality already exists in heartbeat. This PR standardizes the utility and adds it to logs and metrics hints builder as well.

Why is it important?

A container can always have more than one kind of endpoint that requires different kinds of processing needs. We need to provide a uniform experience across all beats from a hints perspective.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

Author's Checklist

• [ ]

How to test this PR locally

• Check for regressions:
  • Use heartbeat with hints enabled and setup a pod with multiple monitors, this should continue working
  • Use metricbeat or filebeat with hints enabled and setup a pod with hints as usually configured, this should continue working.
  • Repeat the previous test with container-specific hints.
• Test the new feature:
  • Use metricbeat or filebeat with hints enabled, and setup a pod with multiple sets of hints (there are some examples in the docs added in this PR), check that multiple modules are instantiated for the pod.
  • Repeat the previous test with container-specific hints.

Related issues

• Add support for heartbeat hints builder #13119 - PR where this feature was added for Heartbeat

Use cases

[elasticmachine]

Pinging @elastic/integrations-platforms (Team:Platforms)

[elasticmachine]

💚 Build Succeeded

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Build stats

• Build Cause: [Pull request #19330 opened]

• Start Time: 2020-06-23T10:59:54.159+0000

• Duration: 93 min 42 sec

Test stats 🧪

Test	Results
Failed	0
Passed	9432
Skipped	1581
Total	11013

Steps errors

Expand to view the steps failures

• Name: Report to Codecov

  • Description: curl -sSLo codecov https://codecov.io/bash for i in auditbeat filebeat heartbeat libbeat metricbeat packetbeat winlogbeat journalbeat do FILE="${i}/build/coverage/full.cov" if [ -f "${FILE}" ]; then bash codecov -f "${FILE}" fi done

  • Duration: 1 min 27 sec

  • Start Time: 2020-06-23T11:46:20.304+0000

  • log

• Name: Install Go 1.13.10

  • Description: .ci/scripts/install-go.sh

  • Duration: 1 min 32 sec

  • Start Time: 2020-06-23T11:23:55.041+0000

  • log

• Name: Install Go 1.13.10

  • Description: .ci/scripts/install-go.sh

  • Duration: 1 min 32 sec

  • Start Time: 2020-06-23T11:23:57.440+0000

  • log