[GCP] Add firestore ingest pipeline

[ghost]

What does this PR do?

Adds firestore ingest pipeline.

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.

Author's Checklist

• [ ]

How to test this PR locally

Related issues

• gcp.compute data stream does not collect data in correct namespace #4342

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Build stats

• Start Time: 2022-09-30T14:08:18.434+0000

• Duration: 19 min 19 sec

Test stats 🧪

Test	Results
Failed	0
Passed	82
Skipped	0
Total	82

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🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (5/5)	💚
Files	100.0% (5/5)	💚 2.564
Classes	100.0% (5/5)	💚 2.564
Methods	90.816% (89/98)	👍 0.762
Lines	95.752% (1375/1436)	👍 4.223
Conditionals	100.0% (0/0)	💚