Osquerybeat: Populate host.name field

[aleksmaus]

What does this PR do?

Populates host.name field in the beats output documents.

Why is it important?

Addresses: https://github.com/elastic/security-team/issues/3572

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

How to test this PR locally

1. Enroll the agent with osquery_manager integration added to the policy
2. Run live query, for example select * from osquery_info
3. Verify that the host.name field exists and is populated with value

Related issues

• Closes https://github.com/elastic/security-team/issues/3572

Screenshots

[elasticmachine]

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• Start Time: 2022-05-12T18:41:16.491+0000

• Duration: 45 min 43 sec

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Test	Results
Failed	0
Passed	1577
Skipped	0
Total	1577

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