feat(cloudformation): Support Fn::Sub in cases of using a pseudo parameter

[bo156]

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Description

Pseudo Parameter in CFN is a parameter which is dynamically available (see reference).
As we do not render it on buildtime, we want to handle this case by keeping the reference itself without the
value, so we can at least build a semi-full resource.

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/pseudo-parameter-reference.html

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

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Generated description

Below is a concise technical summary of the changes proposed in this PR:

Introduce support for handling Fn::Sub with pseudo parameters in AWS CloudFormation templates. The CloudformationVariableRenderer class now includes a method _handle_sub_with_pseudo_param to manage these cases by retaining the reference without the value, ensuring a semi-complete resource build. The PseudoParameters enum is added to cfn_keywords.py to define available pseudo parameters. Test cases in test_render.py and new JSON/YAML resources validate the changes, ensuring that pseudo parameters are correctly processed and that the Fn::Sub function behaves as expected.

Topic	Details
New Test Resources	Introduce new JSON/YAML resources and test cases to validate the Fn::Sub function and pseudo parameter handling in CloudFormation templates. Modified files (5) tests/cloudformation/graph/graph_runner/test_running_graph_checks.py tests/cloudformation/graph/graph_runner/external_graph_checks/jsonpath_policy.yaml tests/cloudformation/graph/graph_runner/resources/jsonpath_policy/pass_str.json tests/cloudformation/graph/graph_runner/resources/jsonpath_policy/fail_dict.json tests/cloudformation/graph/graph_runner/resources/jsonpath_policy/fail_str.json Latest Contributors(2) User Commit Date nimrodkor@gmail.com Move-test-yamls-for-k8... January 24, 2022 @gruebel add-pre-commit-flake8 December 12, 2021
PseudoParameters Enum	Add PseudoParameters enum to define available pseudo parameters in CloudFormation templates. Modified files (1) checkov/cloudformation/parser/cfn_keywords.py Latest Contributors(2) User Commit Date @gruebel add-AWS-SAM-support-2013 November 30, 2021 @Saarett changed-a-few-enms-to-... August 17, 2021
Renderer Enhancement	Enhance the CloudformationVariableRenderer to handle Fn::Sub with pseudo parameters, ensuring references are maintained without values for semi-complete resource builds. Modified files (1) checkov/cloudformation/graph_builder/variable_rendering/renderer.py Latest Contributors(2) User Commit Date @gruebel break-general-remove-P... October 04, 2023 maxam@post.bgu.ac.il add-exception-for-dict... June 09, 2022
Test Updates	Update test cases to validate the handling of Fn::Sub with pseudo parameters, ensuring correct processing and expected behavior. Modified files (3) tests/cloudformation/graph/graph_builder/test_render.py tests/cloudformation/graph/graph_builder/resources/variable_rendering/render_sub/yaml/test.yaml tests/cloudformation/graph/graph_builder/resources/variable_rendering/render_sub/json/test.json Latest Contributors(2) User Commit Date @gruebel chore-use-mock.patch-f... January 17, 2023 @Saarett CFN-Func-is-not-evalua... October 07, 2021

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[SteveVaknin]

Nice 👌