Use Insta for CLI Integration tests

[chaluli]

Describe the improvement you'd like to request

Improve how new integration tests are created and updated using insta (cf https://github.com/cedar-policy/cedar/blob/656d15965ea153b1a9c71ec1d9b312104a377967/cedar-policy-formatter/src/pprint/fmt.rs#L246).

Describe alternatives you've considered

Don't do it and keep the status quo.

Additional context

No response

Is this something that you'd be interested in working on?

• 👋 I may be able to implement this internal improvement
• ⚠️ This feature might incur a breaking change