fix(terraform): use resource address in entity path

[piax93]

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Description

All terraform checks that rely on Cloudsplaining use the entity_path, and consequently the resource name, to cache parsed policies. This is a problem when dealing with IAM resources managed in a for_each block.

The fix is to use the full resource address to infer the resource name, rather than just it's un-indexed form, so that entity paths will result into something like ...:<resouce_type>.<resrouce_name>[<resource_index>] and the IAM policy caching won't get broken anymore by overlapping keys.

I am not sure if __address__ is available in all cases when this code is called, I know for sure it is the case when parsing terraform plan outputs, which is where this issue appears the most, so I made the name extraction conditional on the field being present to avoid breaking other input cases.

Fixes #7337

Checklist:

• 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