[GCP] Add GCP Metrics Data streams

[legoguy1000]

What does this PR do?

Migrates GCP Metricsets to GCP package

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).

Author's Checklist

• [ ]

How to test this PR locally

Related issues

• Closes Migrate some Metricbeat modules to GCP package #490

Screenshots

[elasticmachine]

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• Start Time: 2021-11-03T12:06:34.828+0000

• Duration: 3 min 38 sec

• Commit: a8e9959

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🤖 GitHub comments

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[endorama]

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[endorama]

Hello @legoguy1000, I spent some time on this PR but the changes is very big and is difficult to review. Moreover I would like to add tests alongside all these changes, but this proves difficult.

As I really value this contribution and I would like to move it forward, here is my proposal: I created a new branch called gcp-metrics. May you to split this PR into multiple ones (one for each datastream/metricset) and target gcp-metrics as base branch?
Doing that would allow better review and being able to merge and add tests in smaller batches, which in the end will speed up inclusion.

What do you think? From your side the only additional effort would be to split this PR, as then I would be able add the missing pieces as needed.

Thank you!

[legoguy1000]

Do you want me to make each log/metricset its own policy template so they can show up individually like AWS or like I had it and just group Logs and Metrics?

[endorama]

@legoguy1000 As in the AWS integration I expect each data stream will require it's own policy, but I'll check internally. In any case as we are targetting a dedicated branch I can help performing these changes after merge :)