[AWS][API Gateway] Set dimension fields

[constanca-m]

What does this PR do?

Set the dimension fields for API Gateway data stream.

The dimension fields are:

• ECS fields (decision for these fields is here):
  • agent.id
  • cloud.account.id
  • cloud.region
• Other fields:
  • aws.dimensions.ApiId
  • aws.dimensions.ApiName
  • aws.dimensions.Method
  • aws.dimensions.Resource
  • aws.dimensions.Route
  • aws.dimensions.Stage

Passed the tests with 2 elastic agents running at the same time.

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.

Related issues

Relates to #6293.

[elasticmachine]

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Build stats

• Start Time: 2023-07-13T14:05:12.851+0000

• Duration: 56 min 20 sec

Test stats 🧪

Test	Results
Failed	0
Passed	194
Skipped	4
Total	198

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🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (15/15)	💚
Files	93.75% (15/16)	👎 -3.476
Classes	93.75% (15/16)	👎 -3.476
Methods	85.714% (240/280)	👎 -6.443
Lines	85.925% (7387/8597)	👎 -5.199
Conditionals	100.0% (0/0)	💚