[Azure integration] Add guest metrics in vm_compute data stream +dashboards

[narph]

In progress, will update soon

What does this PR do?

Add guest metrics in vm_compute data stream +dashboards

• should expand docs to let users know how to enable guest metrics
• add guest metrics for windows and linux
• add dashboards for windows and linux guest metrics (separate, metrics are not shared)

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).

Related issues

• Closes [Azure Metrics] Update guest metrics stream for compute_vm and compute_vm_scaleset and add dashboards #1452

Screenshots

Guest Metrics for Windows

[elasticmachine]

Pinging @elastic/integrations (Team:Platforms)

[elasticmachine]

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Build stats

• Start Time: 2021-08-18T13:03:38.214+0000

• Duration: 13 min 54 sec

• Commit: e31b8f3

Test stats 🧪

Test	Results
Failed	0
Passed	131
Skipped	0
Total	131

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