[Cloud Security] add external id field

[Omolola-Akinleye]

Proposed commit message

I'm adding external_id input var field for the cloudbeat/cis_aws input. We will use Role ARN and External ID fields
to establish trust with Elastic.

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.
• I have verified that any added dashboard complies with Kibana's Dashboard good practices

Related ticket: Add Cloud Connector Support for Agentless CSPM AWS Integration

[elastic-vault-github-plugin-prod]

🚀 Benchmarks report

Package cloud_security_posture 👍(1) 💚(0) 💔(1)

Expand to view

Data stream	Previous EPS	New EPS	Diff (%)	Result
findings	66666.67	47619.05	-19047.62 (-28.57%)	💔

To see the full report comment with /test benchmark fullreport

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: d58e971