[ThreatQ] Adding threat.feed ECS fields and dashboards

[P1llus]

What does this PR do?

Adds threat.feed fields and dashboards to the ThreatQ integration

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.
• I have verified that Kibana version constraints are current according to guidelines.

[elasticmachine]

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Build stats

• Start Time: 2022-01-19T08:20:05.430+0000

• Duration: 14 min 38 sec

• Commit: d9ff700

Test stats 🧪

Test	Results
Failed	0
Passed	8
Skipped	0
Total	8

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