Add support for CloudTrail Digest and Insight Logs

[leehinman]

What does this PR do?

Adds support for AWS CloudTrail Digest and AWS CloudTrail Insight Logs

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
  - [ ] If I'm introducing a new feature, I have modified the Kibana
  version constraint in my package's manifest.yml file to point to the latest Elastic stack release (e.g. ^7.13.0).

How to test this PR locally

Setup CloudTrail with Insight logs.

Related issues

• Closes [Elastic Agent] AWS integration - Add an option to limit the files that are downloaded for CloudTrail logs #1022

Screenshots

[elasticmachine]

Pinging @elastic/security-external-integrations (Team:Security-External Integrations)

[elasticmachine]

💚 Build Succeeded

the below badges are clickable and redirect to their specific view in the CI or DOCS

Expand to view the summary

Build stats

• Build Cause: Branch indexing

• Start Time: 2021-06-08T22:28:33.000+0000

• Duration: 15 min 54 sec

• Commit: c094a56

Test stats 🧪

Test	Results
Failed	0
Passed	247
Skipped	0
Total	247

Trends 🧪

[kaiyan-sheng]

👍