Add support for nanosecond precision timestamps

[kvch]

What does this PR do?

This PR adds support for nanosecond precision timestamps in Beats. It is the updated version of #15872

Why is it important?

When events come faster then milliseconds, ingested events might have the same @timestamp field. So there is no way to order them correctly. By making the timestamp more precise we can avoid such problems.

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.

Related issues

Closes #15871

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• Start Time: 2022-05-12T17:10:38.700+0000

• Duration: 105 min 48 sec

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Test	Results
Failed	0
Passed	22618
Skipped	1938
Total	24556

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