chore: store examples in YAML

[nikpivkin]

In this PR:

• Terraform and CloudFormation examples moved from cf.go and tf.go to yaml,
• all checks now refer to the yaml examples
• added command for formatting examples

Although all the examples for a single check are in a single file, we need to reference it from multiple check fields. I suggest adding a new examples field that will point to a single file, while maintaining support for the current method of referencing examples for backwards compatibility.

Old example files will be deleted in another PR as they are still referenced by Go checks.

[nikpivkin]

Will be ready for review after the release of Trivy v0.57

[simar7]

One thing to keep in mind with the examples is the avd generator. I believe it uses the go files as well. Could you confirm that @nikpivkin?

[nikpivkin]

@simar7 I'll check, but as far as I remember avd-generator uses generated md files.

[nikpivkin]

avd-generator uses only generated .md files https://github.com/aquasecurity/avd-generator/blob/main/docGen/defsec.go#L151-L161

[nikpivkin]

Maybe we should change the file schema to the following?

id: avdid
examples:
   terraform:
   cloudformation:

This will allow us to associate examples and checks without using the trivy and trivy-checks packages to run the tests. To do this now, we need to load all the checks and then load all the examples based on the check metadata.