feat(terraform): Handle IAM trust policies with external ID condition

[tronxd]

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Description

Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.

Fixes # (issue)

New/Edited policies (Delete if not relevant)

CKV_AWS_61

Description

• Handle trust policy with an sts:assumeRole action and a sts:ExternalId condition to be classified as passing

Fix

How does someone fix the issue in code and/or in runtime?

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my feature, policy, or fix is effective and works
• New and existing tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules